The Ynnari are a problem!
The issues I had with the army in 7th Edition have not changed in 8th. In fact, while attempts have been made in the Index to weaken them. The issue is being able to take extra actions. Not only in your own turn but in your opponents turn. I've played several games with the army now, and feel confident in this assessment.
Strength From Death
In a nutshell - When a unit dies, a Ynnari unit with this rule within 7" can immediately take an extra action. Each unit death can only trigger one Ynnari unit. Each Ynnari unit can only use this ability once per turn. The extra actions are
- Move or Fall Back, as if it was the movement phase, you can even Advance if you wish
- Attempt to cast a Psychic Power, as if it was the psychic phase
- Make a Shooting attack, as if it was the shooting phase, even if it Advanced or Fell Back
- Charge, as though it was the charge phase, even if it Advanced or Fell Back. The opponent can Overwatch as normal.
- Fight, as if it was the fight phase
Fire Dragons can destroy a Vehicle with their Fusion Guns, then Soulburst to shoot the second one. Or that death can allow a unit of Banshees to move closer to the enemy to guarantee a successful charge in the charge phase.
Of course, it's dependant on getting that kill. Leave one model in the unit alive, and no Soulburst for you. But wait, in your opponents turn (or your fight phase) when one of your units die, you can trigger Soulburst and take any of the above actions. Lose a unit to shooting and retaliate with another unit. Or move the second unit out of range/line of sight. Enough triggers can allow you essentially an extra turn during your opponents turn, and if you are really lucky, an extra turn during your own. While it may be costing you units, you can sometimes take 3 effective turns to your opponents 1.
Changes Made
In an attempt to weaken the Ynnari between 7th and 8th, a few changes were made.
Firstly, it was restricted to Infantry and Biker units. In 7th, Wraithknights could Soulburst, which is as horrendous as it sounds. Now you are limited in what units can do it. Also, you cannot Soulburst from your own Transport dying while you are in it.
As Morale has changed, you cannot Soulburst if the last model in a unit is removed due to Morale. This is because the model is fleeing the Battlefield, not dying. It also makes the Morale phase one where Soulburst is unlikely to happen.
The FAQ changed the army composition to have the units in a Detachment to have to all have the Ynnari keyword. No more mixing them in with your Aeldari to take the best units with the best abilities. Some Harlequin units are better with Rising Crescendo for instance.
Razorwing Flocks got changed. Their points value and minimum squad size were both increased as they were a cheap source of sacrificial units to trigger Soulburst.
Finally, an update to the FAQ stated that not only did your Detachment have to all have the Ynnari keyword, but it has to be lead by one of the Ynnari characters.
Were these changes enough?
No.
The change in which units could Soulburst only affected the Wraithknight and the Wraithlord. Everything else that can't do it, couldn't in 7th. It's only those two that are hit. Activating a Wraithknight again is a scary prospect, so this change has been positive.
The Morale rule fits the flavor of both rules, so seems fine. It does remove a phase that Soulburst can happen in.
Those two changes are positive. How much of an effect they have seems minimal though.
Changing the keyword requirement is interesting. In theory, it stops you min-maxing your unit selection. In practise, Strength from Death is actually better than the other options. There are arguments to be made for Rising Crescendo, but timely Soulburst makes a difference. Power From Pain takes time to kick in and the "Feel No Pain" aspect seems counter to wanting your units to die. Battle Focus is.... Not good. I think the rule needs altering or the Asuryani need altering to take more advantage of it. But that's a topic for another day. The extra actions from Strength From Death easily outweigh them all.
Removing the cheapest way of triggering it doesn't change much. People using that tactic will just move to the next cheapest option. It's something being shown across all the factions, as large units of cheap models are being used to screen characters and hold objectives. The problem here is using minimum size units as fodder though. Forcing your opponent to kill the unit, either by throwing it into combat or screening a character they want to kill. This gives the Ynnari a bit more control of when and where Soulburst triggers.
Finally, and most recently, for your army to be Ynnari, it has to contain and be lead by either Yvraine, the Visarch or the Yncarne. I'm sure this change meant well. They even updated the Visarch to have an invulnerable save since he has a Forceshield modelled onto his wrist.
It's crap. I haven't used the Yncarne as it's a little expensive and the Visarch still looks the worst on paper. However, Yvraine is the cheapest, gets to cast 2 of the Ynnari exclusive powers a turn, gets +1 to cast and deny rolls. I've seen one player use her to give a squad of Dark Reapers the ability to re-roll 1s on hit rolls, then Soulburst to shoot in the Psychic Phase. This essentially used her and the 6 Reapers to act like an Autarch and 12 Reapers, every turn. For less than the cost of 12 Reapers! I'm sure there are more efficient uses for her.
How do I think this problem could be fixed?
Firstly, if nothing else, Battle Focus needs looking at. Currently competitive Asuryani armies are entering tournaments as Ynnari because Strength From Death is clearly a better option and they lose nothing making the switch. Having to make your Warlord one of two powerful Psykers whom are decent in assault isn't a cost, it's a bonus. With this weeks announcement that the Craftworld Codex is coming in the next 5, it's possible that this step has already been taken. So in that regard, it's a case of wait and see. Hopefully it will either return the functionality of the rule to allowing a movement after shooting or the range of units that benefit from the rule will increase. There are too many non-Assault weapons in the Index list for many units to actually use Battle Focus.
Secondly, release an Ynnari Codex. This would allow you to print a conclusive list of units that are allowed the keyword, and then give them an appropriate points cost. A unit with the ability to trigger Soulburst is clearly more powerful than an equivalent unit that can't. You can also scale the point increase based on the units ability to destroy targeted units. A unit of Fire Dragons or Wraithguard is going to have an easier time killing a Vehicle or Monster and triggering it's own Soulburst that a unit of Dire Avengers. Especially as the range of their weapons means that most of the time they will be within 7" of a target anyway.
You can't make them too expensive however, as different units are designed to kill different targets with varying degrees of efficiency. It is clear though that the potential for a unit with D-Scythes to kill a small unit, then kill another in your turn plus killing a unit on Overwatch, then another unit in your opponent's turn is very powerful. Obviously that requires your opponent to have four units close enough to the Wraithguard, but some armies like World Eaters and Harlequins are assault-based and can't help it.
While there is an argument for the competitive meta settling on counter-units and counter-tactics (while hoping the Ynnari don't adapt), the army is not fun to play with or against in a casual setting. You can say "Just don't play the army in casual games" but with the focus on Narrative-esque play with campaigns like Konor, and the Gathering Storm leaving Iyanden firmly in the Ynnari camp, that's not a great solution in the long term. It never feels good when you stomp an opponent in a very lopsided game, shrug your shoulders at their discomfort and say "Sorry, but the army is actually flavourful".
The previous flavour of Aeldari armies, especially Asuryani, was powerful units but an inability to handle a battle of attrition. With the Ynnari, you get powerful units and a mechanic that punishes your opponent the longer an attrition battle goes on.