Remember how Eldar were a kinda underpowered, bottom-tier army that no one used in 7th Edition? Well GW fixed that problem.
So the new Gathering Storm book is all about Eldar- excuse me Aeldari, as the book uses for an umbrella term. It actually presents an entirely new faction for the game (as if it didn’t have enough already), though only on a nominal level- the Ynnari, worshippers of the Eldar god of death are really just existing units from various factions drawn together into a “meta-faction” that is going to cause all kinds of havoc for ITC bookkeeping.
There’s been a lot of talk about the book ever since it was first rumored, unsurprisingly, so in this review we’ll talk a walk through the new rules to familiarize ourselves and to get a feel for what they do and what potential they have as well as whether they measure up to the hype. I’m only going to discuss the mechanical aspects of the book- there’s certainly lots to talk about on the fluff side of things, from artwork to storyline to themes, but there are other writers that can handle that part and this is gonna be long enough as-is.
DIE DIE DIE (And then Shoot, Shoot, Shoot)
The big splash for this release is the Ynnari faction, which are essentially a new subtype of Eldar models in the same way that the race is currently split into Craftworlds, Dark kin, Corsairs, Harlequins, etc. Ynnari are drawn from existing models and codices- either Craftworld, DE, or Harlies, including all of those factions’ basic formations- and replace the codex special rules (Battle Focus, Power From Pain, Ancient Doom) with the Strength From Death rule, which is a doozy. You can only field Ynnari models in their unique detachment (the Reborn Host) or one of the Ynnari formations from the book, so no Combined Arms or Allied detachments for them.
Whenever a unit- either yours or your opponent’s- dies within 7″ of a one or more units that have Strength From Death, you can pick one of those units to immediately take a Soulburst action. A Soulburst lets you make either a normal movement, shooting, or assault action as though it were the appropriate phase, but no unit can Soulburst more than once per turn. Even with that limitation, however, Strength From Death is an incredibly strong ability because it not only lets you double up on your actions, it also gives you lots of options with which to break your opponent’s plan and cause shenanigans. Out-of-sequence actions are always powerful- remember the uproar when people found out about Overwatch?- and Soulburst is no different, with a lot of possibilities for ways to abuse it.
Strength From Death’s range is quite short, but the key thing to remember is that it will trigger off any unit dying. Kill a transport? That’s a free action that you can use to shoot the guys inside. Wipe out a squad in close combat? Go ahead and take a free shot, or charge a new unit. One of your squads got wiped out? Move someone nearby to a safer spot. Some of your guys get shot to death? Charge into another nearby unit to turn off some of their firepower.
Now, Strength From Death certainly has its limitations- you need to be really close to things that are dying, which can be hazardous against many armies, and if you charge you won’t get to actually resolve the assault until the normal time during the Fight sub-phase that turn. You also can’t Soulburst with vehicles, with units that are pinned, with units that are locked in combat, or those that are already falling back. But when you’re doing it right and facing down the right army, it’s basically just gonna be two full turns back-to-back. Having to give up Battle Focus is certainly not a trivial loss, but when the gain is so high it’s more than worth it.
Soulburst is gonna force some changes to how Eldar build armies and how they play; whereas Craftworlds right now prefer to play a sort of “cat and mouse” game where they hit the opponent while remaining on the edges of their range, Ynnari armies want to get up close and personal with the enemy so that they can inflict maximum casualties and thus gain the benefits of Soulbursting. This will mean that Windriders are going to be less of a feature (although still useful) and Wraithguard probably will make a reappearance; Warp Spiders and Wraithknights will, of course, remain popular. There are a lot of risks to this sort of playstyle, but with your army often getting to essentially go twice for every turn the enemy takes, I don’t think it’s going to really matter what those risks are.
It’s worth noting that the Ynnari don’t have access to all of the stuff that normal Eldar do- they can’t take Combined Arms or Allied detachments, they can’t use most Forge World units, and they aren’t able to bring any of the Haemonculous Covens stuff (including the variants of those units from the normal DE codex.) Once again, though, while these are non-trivial losses I don’t think they’re going to stop players from using the Ynnari; Warp Hunters and Hornets are powerful, but not as good as shooting twice with everything.
I’ve mostly been talking about the Ynnari in the context of Craftworld Eldar, and that’s not an accident- Craftworld Eldar are easily the most powerful of the three books to get rolled together, so it makes sense to focus on them. However, Harlequins and Dark Eldar certainly have things to offer the army as well- Webway Portals, of course, but also cheap transports, good characters in the Elites slots, MSU Reavers, etc, etc. However, whereas Craftworld Eldar have a choice to make of whether or not they want to use Ynnari rules (as they give up some significant stuff to get them), Dark Eldar and Harlequins have no real decision there- Strength From Death absolutely blows Power From Pain out of the water and Harlequins don’t actually lose anything at all by going over to the Ynnari. Expect to see even the last few dregs of DE and Harlie players vanish from the competitive scene as they gain access to far better tools in the new book.
Unique Features That Every Army Has
The Ynnari detachment, the Reborn Warhost, is a bit of an interesting thing on its own. Apart from the formations in the book, it is the only way to use a Ynnari force- no Combined Arms detachments, no Allied detachments, etc. Superficially it is basically just a Combined Arms- you have the same minimum and maximum slots available (picked from a list of basically all of the Eldar, DE, and Harlie units) but you can also include any number of formations (again, picked from the full list for those factions) as part of the detachment in the same way that the various Decurion-style detachments work. This combination of both force org slots and formation slots is something we haven’t seen before, and it really only adds to the power of the Ynnari as a whole- you can cherry-pick the best stuff that each of the armies has to offer to fill requirements and then also stack the formation benefits on top of the detachment abilities.
And the detachment’s abilities are pretty significant. It has the usual reroll on the Ynnari warlord chart, of course, and it grants all models in it Stubborn and the ability to ignore morale checks for taking 25% casualties so long as they have a friend within 7″. (One wonders why 7″ is the new standard for everything Ynnari- is it just to make those handy measuring templates useless?) More importantly, when a unit dies you get to pick two of your units within 7″ to Soulburst; where a “normal” Ynnari force might struggle a bit to make full use of its free actions, a Reborn Warhost certainly will not. Even if there were other options for how to field them, I doubt that anyone would bother with anything apart from the Warhost, as its abilities make a powerful ability even stronger while still allowing you to cram all the formations you could possibly want into it.
The Ynnari warlord traits, meanwhile, are fairly underwhelming (with one exception.) It Will Not Die for the warlord only is complete garbage- even the Personal table version of that at least gives you Fearless as a secondary bonus. The choice of Furious Charge, Move Through Cover, or Hit and Run each turn is actually pretty decent- those are useful rules that can sync well with a lot of units and the ability to shift between game turns is very neat. Instant Death on hit wound roll of 6 is a cute trick but not that exciting at the end of the day; most Ynnari warlords just aren’t that great in a fight against the “real” characters in the game. Fearless for the warlord and all Ynnari within 7″ of them is decent, but not amazing; you already have several morale-related abilities in the detachment anyways. Soulbursting with a radius of 14″ for the warlord and their unit is pretty good; it gives you a lot more flexibility in that respect and will often let you trigger when other units can’t. I’ve saved the big exception for last, however: the warlord (if they are a psyker) can pick, rather than roll randomly, their psychic powers. So yeah, all of those fantastic powers in the Telepathy, Divination, Fate, and Revenant trees? Just go ahead and take whichever ones you want. This alone is probably enough for a Farseer (or whoever) to roll on the Ynnari warlord table, because it can be pretty game-breaking to get. It does, however, cause some issues with the way ITC generates psychic powers and warlord traits, since the former comes before the latter and thus essentially renders that warlord trait blank- something they may need to address in the 2018 season. (Grey Knights also had some issues with this previously, although nothing that couldn’t be resolved.)
Speaking of which, lets’ dive into the Revenant psychic discipline. Available only to Ynnari psykers and adding to any other tables they can otherwise select from, Revenant is a bit of an odd mix of abilities that mostly focus on offense. The primaris, Spirit Hook, is a focused witchfire that does a S6 hit (if your Leadership is higher) or a S3 hit (if it is equal/lower) to one enemy model, with no cover/armor allowed. This will pretty consistently kill one model but is probably not that exciting overall; triggering its focus effect will be nice for picking off a special weapon but otherwise it will struggle to hurt stuff like MCs and it is literally unable to damage a vehicle. As most disciplines are heavily defined by their primaris, this isn’t a great starting place. The first power on the table doesn’t do the discipline any favors, either, as it just gives the caster and all units within 7″ a 6+ invulnerable save. Yes, what Sisters of Battle often forget they have for free, Ynnari are casting a psychic power to get.
Thankfully, however, the rest of the table improves steadily beyond that. A very solid nova is next on the list- standard 9″ range and 2d6 S3 AP2 Ignores Cover hits with the Pinning rule make for a pretty nice power overall; although S3 isn’t exciting, needing 5s or 6s to wound most targets, having both AP2 and Ignores Cover built in are pretty excellent- and to top it all off, it’s WC1. The next power is WC2 and is pretty simple- one unit within 24″ that has Strength From Death immediately makes a Soulburst action. While WC2 is a bit on the expensive side as things go, taking a full action with any unit has a lot of potential and any other faction would kill for such an ability- that Ynnari consider it merely acceptable is a good sign of how strong they are.
Also at WC2 we have a less impressive power- a blessing that gives +1 to Weapon Skill, Ballistic Skill, Initiative, Attacks, and Leadership. As most Ynnari units are shooting-focused, this provides only a small boost to their effectiveness; however, if you can slap it onto a melee unit it can be a pretty huge swing. A good power all things considered, just in the wrong faction. The discipline rounds out with two more witchfire powers; the first has only a 12″ range (though you’ll be wanting to be close to the enemy anyways, so it hardly matters) and gets a number of S4 shots equal to the number of models in the target unit- hilarious against a Barkstar or the like. If it does even a single casualty, you can immediately Soulburst with one of your units within 7″ of the target. Lastly, we get a Gaze of Ynnead to match the various other Gazes that have been added into the game, but Ynnead’s eyes are apparently kinda weak compared to Magnus or Tzeentch’s and it’s “just” a S10 AP1 hit that ignores cover and invulns. Bypassing all defenses is a nice trick, but for WC3 you kinda want more than just a single hit- it’s not even precision or anything, so it’s very possible you’ll just kinda Shake a Rhino with it or whatever.
All in all the Revenant discipline is solid, but not amazing, and most Ynnari psykers will have better options available through other disciplines. However, if you’re forced to roll on it or particularly want some of the powers, it’s not a complete wash with the exception of the shitty 6++ spell; most of the time, you’ll get a solid shooting spell or a free Soulburst (or both) out of it.
The same can’t be said about the Ynnari relics, however. Ynnari models can either pull from their normal relic list or the Ynnari one, but very rarely will you care enough to take from the latter; they aren’t awful for the most part, but their effects are usually quite underwhelming. Corai Heg’s Locket is one of the better options at 15pts; if you kill any models in the Fight sub-phase, you gain a wound back on a 3+ (which can potentially save you from being killed yourself.) It’s a pretty neat little trick and due to the wording on it, you can “come back to life” no matter how much damage the enemy does to you, but the need for a roll means you can’t rely on it absolutely. The Hungering Blade is also 15pts and gets you a Fleshbane attack that gets you all your wounds back if you kill an Eldar of any variety during combat; it’s a cute trick in the mirror match but mostly just won’t come up and you’ll be paying points for something you already have. The Lost Shroud is in the mold of several other “character gets bonuses but stops being an IC” items that have almost always been terrible, and it’s no exception; 35pts for Eternal Warrior, Feel No Pain, and It Will Not Die just isn’t very good when you’re sitting out in the open on your own like an idiot. Mirrorgaze is a weird item- it’s not cheap at 30pts, but gives you the Blind, Night Vision, and Counterattack rules. Blind is a bit unreliable against most armies, but when it works it’s fantastic and Ynnari can easily end up hitting two or even three targets in a turn, so it has a lot of potential to do work- the question is whether it will be better than the faction relics that the character already has access to, as their are some very good ones in the various Eldar books. Song of Ynnead is the standard “cheap pistol relic” and gets you a 2+ poison Bladestorm combo that will force a morale check if you do even a single wound with it; nothing really exciting there. Finally, the Soulsnare is the Ynnari version of the Dark Eldar “death orb” idea, and as such it’s just awful. 8″ range is a bad way to start things, and then you add in S3 and one use only and you have a weapon designed for failure on every possible level. It causes Instant Death, I guess? So one in twelve games you’ll get really lucky and throw it on a Riptide and ruin his day, but the vast majority of the time it will scatter off or fail to wound or they’ll pass a cover/invuln save and your stupid egg won’t do anything.
Data Between the Sheets
Yvraine is the first of the three new characters featured in the book; an Eldar who has been part of basically every possible faction and the herald of Ynnead, her game rules place her as a psyker with a very unusual statline and some respectable (if not overwhelming) combat capability. She starts out with a Succubi’s numbers- WS/BS/I 8 as well as a good number of attacks and wounds. She only comes with a 6+ armor save, but like all Eldar psykers she gets a 4+ invulnerable- however, she does not have a Ghosthelm to negate Perils results or Runes of the Seer to reroll psychic/deny checks, so you’ll need to be a lot more cautious with her. Her Gyrinx familiar makes up somewhat for the latter, as it gives her an extra d3 warp charge to use each turn. Although only S3/T3, she has Eternal Warrior and heals a wound anytime a friendly model is slain within 7″ of her (provided she rolls a 4+ first), so she can be surprisingly tanky by selectively Look Out Sir-ing wounds away to heal herself, then taking a couple shots on the nose. If the slain model was a psyker, she gains a mastery level and new power immediately as well, though she maxes out at ML4 (and starts at ML2.) Yvraine can generate from the Sanctic and Revenant disciplines, which limits her a lot compared to most Eldar, but she still makes a fairly passable psyker overall. Her real surprise, however, comes in the sword she carries- it’s +1Str AP3 and Instant Death, and combined with her high stats it can make her shockingly dangerous to many of the lower-tier characters in the game and even some MCs.
All in all, Yvraine isn’t a bad character, but since she clocks in at a cool 200pts, she really is asking for a lot of trust in her abilities to pay off. Although one of the most resilient psykers you’ll see (provided she hangs out with a good-sized squad), her lack of movement options and middling power choices will rarely make her an enticing option for Ynnari players- the Farseer, Spiritseer, and Shadowseer all have most of her tricks with a much lower price tag. Even her fixed warlord trait (Soulburst within 14″) doesn’t earn her much credit, and I don’t think you’ll see a lot of players running her unless they are specifically looking to surprise folks with a wacky combat psyker.
Next up on the list is the Visarch, who is I guess some sort of bodyguard dude? (Sorry, Zyekian, it was a good guess.) He actually has a worse statline than the person he is protecting, which seems a bit odd, but with Rampage and Precision Strikes (plus Eternal Warrior that seems common to all the Ynnead models) he actually comes out hitting harder in a lot of cases. He benefits from a 3+ armor save for his distinctive-but-apparently-not-unique armor but has no invulnerable save at all, something of a crippling flaw on a nominal combat character. Like Yvraine, the Visarch heals a wound on a 4+ anytime a friendly model within 7″ is slain; his trigger gives him an extra attack if the model was a character, capping out at seven. He also generates a warlord trait from the Ynnari table regardless of whether he is your warlord or not, which is a decent little bonus. Finally, Yvraine can always LOS wounds to him without a roll and he can always take her place in a challenge. He also carries one of the Croneswords, and like Yvraine’s it is quite good- +2Str AP2 and makes all enemy units within 3″ use the lowest Leadership rather than the highest. While this isn’t a big deal against some armies (Necrons, Tyranids), against most it will be equivalent to a penalty of between -1 and -3, depending; note that the penalty is for all purposes, not just checks- he’ll make your Psychic Shriek hit harder if he’s in the area.
The Visarch is cheaper than the other characters, but at 150pts he is still far from what I would call “cheap.” Like his ward, he suffers a lot from being a slow melee character but also has the additional burden of not bringing as many utility abilities to the army nor actually being tough enough to get into combat and last the way he wants to. Sadly, the Visarch is easily the weakest of the three new models and even casual players will likely find him somewhat unappealing- I mean, the poor idiot doesn’t even have assault grenades, for crying out loud.
Now, the more-differenter-Avatar is another matter. The Yncarne’s statline is almost identical to the regular Avatar’s is- slightly lower WS/BS and an extra attack instead. However, where its counterpart is just a big, dumb MC on foot the Yncarnae brings a lot of nice tricks to the table. For one, it’s got Deep Strike (and in fact must do so) as well as Eternal Warrior, giving it some good immunities. For two, it’s a ML3 psyker that generates off the Sanctic and Revenant disciplines (even though it is a Daemon.) For three, it gives all Ynnari models within 12″ Fearless and Feel No Pain, which not only makes it significantly tougher but also lets you shrug a bit more damage with other units as well. And, like the other two, it heals a wound on a 3+ whenever a friendly model is slain within 7″, though it doesn’t get a bonus “trigger” and can’t be part of a squad, making the ability slightly less useful overall. It carries a very strong weapon- Fleshbane, Armorbane, and Soul Blaze all packed together, giving it the ability to consistently wreck most targets well before they get to do anything (provided it can get into combat, of course.)
But the real killer is its last ability, and it’s the one that makes up for the 275pt price tag as well as differentiates it from the “wandering around on foot” mold that most fancy named MCs get stuck into. While the Yncarne must start in Deep Strike reserve, anytime a unit is slain (friendly or enemy) you can immediately place the Yncarnae as close as possible to the spot they died at (but still 1″ from any enemy models.) It can choose to do this whether it’s in reserve or on the table, though it is disallowed from charging the turn it does so- but if you “teleport” it on the enemy turn after they kill one of your units it’s certainly free to charge on yours, and of course if you move it on your turn you can potentially charge it into something with a Soulburst action on the enemy turn. This ability to bounce about the field virtually at will and move into (or out of) trouble spots is amazing and I wouldn’t be surprised to see the Yncarne work its way into some very sneaky lists; however, as it competes with the mighty Wraithknight for the army’s Lord of War slot (and costs nearly as much as the big boy), you’re going to need some very creative use of its abilities to make it work out. Still, I think the Yncarne is going to see a lot of testing by the top players because its ability is wholly unique in the game and has a lot of possibility to screw with people’s plans- keep an eye on this one.
Let’s move into the formations: the Triumvirate of Ynnead is the counterpart to the Imperial trio; it consists of all three of the new models and gives Fearless to any units within 12″ of at least two of them and Fearless to everything if all three are in play. It also adds +1 to all of their rolls to regain a wound, which is probably the more relevant aspect. As expensive as each of them are, however, you’re gonna be hard-pressed to want all three at once, especially as they have very little synergy with each other.
The Soulbound Vanguard is supposed to represent the “core” of the Ynnari, the original recruits to the cause. With two squads of Dire Avengers, one of Incubi, and one of Wyches it’s not a terribly exciting start; they all get +1 WS/BS if either of the named Ynnari characters is joined to their unit as well as Furious Charge while they are within 7″ of another member of the squad. They can also Soulburst off a unit within 14″ rather than 7″, which is actually pretty nice. It’s a very flavorful formation but not a terribly strong one; the need to join expensive characters to the squads to get benefits is not great and the units themselves are nothing particularly special.
The Aeldari Bladehost is a bit of an awkward one. It starts with two Wyches, two Troupes, and two Storm Guardian/Black Guardian units- so obviously going for a melee theme. If two units from the formation are locked in combat with something they have Hatred and if three are they have Preferred Enemy- decent bonuses, and probably needed if they’re actually going to win a fight. It pales compared to the second ability, though- once per turn when you Soulburst with a unit from the formation for the first time, all the units in it get to Soulburst instead. This can give you some absolutely ludicrous action efficiency, but the fact that none of the units in it are particularly good at shooting (with the possible exception of Black Guardians) means that you often won’t be able to make great use of it.
Ynnead’s Net is the requisite jetbike-themed formation; you get one unit each of the different types of jetbikes, from Warlock Conclave to Windriders to Reavers to Skyweavers. Whenever the formation kills an enemy unit (or is itself killed) the Warlocks get an extra warp charge on their next turn, and the whole formation has to start in reserve and arrives on a single roll (with a retry.) When it does so, each of the units moves in from a different one of the table edges, which potentially allows for some neat shenanigans; however, given the hoops you have to jump through it’s probably not really worth the trouble to sneak some Windriders (or Wind Riders, as the formation misnames them) into the enemy backfield.
The Black Host of Ulthwe (It’s Cool I Have Lots of Black Friends)
So far all we’ve talked about is the Ynnari- and certainly they’re the big news in this book. But there’s another little gem hiding in it as well, namely the Ulthwe units. Unlike Ynnari, the Ulthwe stuff get their own unit entries, though they are very nearly just clones of existing Eldar units with a few small differences. All of them are termed as Black Guardian [whatevers] and are available as Guardians, Windriders, Vypers, and War Walkers; the vehicles pay a 5pt tax, whereas the infantry pay 2pts per model, and they all benefit from the Webway Assault rule.
Webway Assault is an interesting mechanic because it’s drawn almost word-for-word from Age of Sigmar; you place the unit by Deep Strike anywhere on the table that is more than 9″ from the enemy and they don’t scatter. This baby version of the Webway Portal is a really powerful ability, since it gives you perfect reliability in where they arrive and the potential to show up on an objective, in inconvenient armor facings, out of Line of Sight of interceptor units, etc.
This means you can potentially put a lot of firepower just about anywhere on the field starting quite early in the game, especially when an Autarch or Comms Relay is guaranteeing the arrival of most of the formation. The Ulthwe Strike Force not only adds to this potential, it opens up some entirely new options for Eldar armies. It consists of one to four of the Ulthwe units (which are technically all Elites) and gives them all Stubborn and Preferred Enemy if there are any Chaos units in the enemy army. (Notably, this does not work on Renegades and Heretics, however.) The best part is in the bonus for maxing out the detachment, though- with all four slots filled, you can make reserve rolls for them starting on the first turn if you want to.
One of the things Eldar often struggle with is dealing with reserve-based armies, and the Ulthwe Strike Force gives some good options in that regard as well as bringing really handy mobility to an already-mobile army. Going second against an enemy shooting army? Like the solo Drop Pod in an Imperial army, Ulthwe can (very nearly) guarantee that you can leave everything in reserve and still be all but guaranteed to have one of your units make its way onto the board to prevent a tabling. But even that aside, Ulthwe units will be quite useful; able to show up deep in the enemy backfield, along the sides, on top of an objective, or any number of other spots they will prove incredibly handy to have around just for the flexibility of putting your units where the enemy doesn’t want to see them. Get rear arc on those vehicles without any need for maneuvering; bypass cover or blocking terrain that’s making it difficult to get shots in; nab an undefended objective or contest a defended one (with a good Run/Thrust move)- the possibilities are virtually endless. I wouldn’t put it as unlike that you will see armies running double Ulthwe detachments, which can be quite cheap in many cases. Though you give up Objective Secured on many of the units compared to bringing them in a normal Combined Arms or Allied, I think the ability to put them exactly where you want when you need them is too huge to ignore and may even make units that are otherwise-underwhelming (like Guardians) worth considering in some circumstances. Ah, who am I kidding? People are gonna use Scat Packs.
One other thing to note here is that Ynnari have access to the various Ulthwe units as part of a Reborn Warhost, though they cannot take an Ulthwe Strike Force in it (since it is not a formation.) Just as with “standard” Craftworld units they will trade out Battle Focus/Ancient Doom to get Strength From Death; once you’ve filled your basic troop requirements with Scat Packs in such an army, there is a strong incentive to go with Ulthwe versions over the normal due to the flexibility they gain for that minimalist price point. Of course, since it is impossible to show up within 7″ of the enemy due to their own rules they won’t generally be able to trigger Soulburst that turn, but you always have the option of bringing them in normally if you think that will be an issue.
So what is all of this going to mean for tournament players? How bad is the damage, in short? Pretty bad, I would say. Ynnari are strong. And not just strong, but significantly stronger than Eldar- already one of the top factions in the game. While there are some reasons not to use them- the Skathach Wraithknight being a big one, since it is such a good tool against armies like GSC and Renegades- I think you will see almost all competitive Eldar players switching over to Ynnari because they offer so many brutal possibilities.
MSU armies are a huge part of the environment right now, from Battle Company to Genestealer Cults to summoning-based armies to Eldar themselves. And Ynnari are absolutely brutal against anything even vaguely MSU, since it is so easy for them to chew through large numbers of units by repeatedly Soulbursting off killing weakened/trivial targets. While for most armies the massed Rhinos of a Battle Company offer significant protection that must be killed before getting to the “meat” of the army, against Ynnari they simply make it easy to trigger lots of free actions as you kill the transports and then the squads inside them in short succession. And while Battle Company might be the worst sufferer from the ability, it is by no means the only one- anything less than a pure deathstar is going to see Ynnari getting 4+ extra actions pretty much every single one of their own turns, and pretty often 2-4 actions on the enemy turn as well.
So yeah, Ynnari are strong. But the question is, are they stronger than all of the other stuff in the game right now? The Split rule is the obvious comparison- it’s just out-and-out stupid broken, but so far ITC has decided not to change it. Ditto a lot of the other things that are around. In fact, the environment is so filled with broken things, it’s hard to even say for sure exactly what effect Ynnari will have on things (other than presumably causing an uptick in players using Eldar models.) Doubtless lots of people will call for a vote to nerf the abilities, but if the past is any indication it may be hard to push such a vote through- and I don’t even know whether it’s really necessary at this point.
(And, to preempt the inevitable calls: no, 8th Edition is not going to fix everything. No, there is not a good reason to think that it will be released within the next 2-4 months, or even necessarily by the end of the year. And even if it was, getting twice as many actions isn’t really the sort of thing the core rules are likely to address, so I think regardless of the fate of the current edition Ynnari will be unaffected, at least in the broadest sense.)
More than that, however, there are a number of issues that Ynnari bring to the forefront and that will affect how they are played. One of the big ones is the nature of casualty removal- do you check whether a unit is within 7″ to trigger Strength From Death from the last model removed (under the presumption that casualty removal is actually sequential, and at that point the model truly is “the unit”?) or do you check from the position all models in the unit occupied before a particular Initiative step resolved or weapon was fired (which would imply that casualty removal is simultaneous and it is only for the benefit of our weak human brains that we perform it sequentially)? And speaking of feeble human brains- the Ynnari will cause a lot of memory issues, as they not only require you to track which units have performed which actions every turn (as it will be quite common for a unit to take its Soulburst action before its regular action.) Worse yet, they can very easily cause nested “chains” of Soulbursts on both yours and your opponent’s turns- for example, some Warp Spiders kill of an enemy unit and the attached IC, resulting in two Soulbursts and the first of those two also kills another unit, triggering another Soulburst “on top” of the original one that still hasn’t resolved yet, etc. It is going to be very, very common for players to forget to resolve the original action that triggered a Soulburst in the first place. And on top of all that, there is the issue of when, exactly, a Soulburst happens- can it interrupt a shooting action that hits multiple units and wipes one of them out? It brings a whole host of timing issues into the game that simply weren’t possible to come up before, or only happened in incredibly niche situations. And that’s not even considering questions like whether or not it can trigger off of a unit fleeing off the table, Deep Strike mishapping, etc.
I don’t want to sound too much like a doomsayer here- I don’t think Ynnari are going to ruin the game or anything like that. I do think they are going to even more negatively impact most players’ opinions of Eldar, but honestly at this stage of things that’s probably a lost cause. And I definitely think they are going to have an impact on the tournament meta, although exactly what is hard to say and I think the army is complex enough that the builds that lots of people are going to post as examples of how scary they are (THIRTY-TWO HUNDRED WARP SPIDERS?!?!!!!11) will be hilariously wrongheaded about actually assessing where the faction is likely to go if not restricted in some way. Strength From Death is a very complex mechanic with a lot of decision points and I think even experienced players are going to need a fair amount of time to really soak it in and understand when and how it is best used.