After play testing with the Wraiths in 5 games I feel I have a good idea on how they perform. I will start with the bad.
Wound generation, it’s a no brainer but at toughness 4 with a 3+ save they want to stay away from anything that can dish out a bunch of wounds in a turn. Boltguns and short range fire isn’t a problem, Its Dark Eldar Venoms and Psycannon, Storm Bolters that we hate. Also Grey Knight Auto Cannon Dreads. They reliably take out 1 Wraith base per turn. That’s pretty much it for the bad.
Now what Wraiths excel at is denying charging opportunity to your shooters. We know Warriors and Immortals fold in combat. With a unit of Wraiths near the centre of your army it becomes an issue to move your assaulters too close. Remember that Wraiths move 12 and ignore all terrain so they will always have an 18inch charge range.
Let’s say a unit of 10 Assault Marines move with 16inchs of the Wraiths in an attempt to clear some Immortals off the table. When assaulting with your whip coils positioned correctly only 4 Marines should be able to strike 1st (If that but let’s be generous). The Marines will get 8 attacks, 4hits and 2 wounds with probably no wounds getting through but let’s give them 1 anyway. The Wraiths hit back with 24 attacks, 12 hits, 10 wounds and 2 rending, 4-5 marines dead. The remaining 6 hit back with a PF and 5 normal guys. 10 attacks, 5 hits, 2.5 wounds 1 more wound on a Wraith with a different equipment type. And then the fists, 2 attacks, 1 hit, 1 wound, Wraiths make 1 save. Marines lose combat by 2-3 reliably!
Another great use of Wraiths in to hunt Long Fangs, Devastators or anyone who likes to sit in the back field. Pair them up with 2 Command Barges and your opponent is going to have hard time with their target priority, when they have 3 painful units jammed down their throat.
Another upside to these bad boys is to use them to soak up fire. Now they aren’t cheap, but a lot of our firepower is. If your opponent is firing everything he has got at the Wraiths with multi wounds and 3+ inv then they are leaving your fire power to reap havoc on their line. And Wraiths will take a lot of fire to drop. Not to mention the cover save they will give to your infantry.
OK so this post has gotten a little big! The real message here is Wraiths are awesome! Use them.
(man I could on about Wraiths for pages)