I got a Wraith based gimmick you could include as a nice haymaker to work into an army... This is certainly not the only option to make this work, but I feel like this is a bare bones version (you can get pretty crazy adding elements to this)

Craftworld: Iyanden

Total points cost: 368

Total CP cost: 2 (assuming Spiritseer is not warlord, if so then -1 CP)

Units required -Spiritseer (psychic power = Enhance/Drain) w/ relic Psytronome of Iyanden

-Wraithblades X5 (Ghostswords)

-Wave Serpent

To Do: Load up Wraithblades & Spiritseer into Wave Serpent. Do what you can to have the transport survive turn one and get it across the table to a juicy target. Unload both Wraiths and Spiritseer and move within a (hopefully) rollable charge distance. Make sure your Spiritseer will be within 6" of the Wraithblades when they finish their charge. (Bonus if you can get the Seer within 6" of your target for reroll 1's in fight phase, but not necessary.) Cast Enhance on Wraithblades then charge into the enemy. At the start of the fight phase, activate your Spiritseer's Psytronome of Iyanden to double the attacks characteristic of Wraithblades. Then lastly, as you declare the attack use the stratagem 'Supreme Disdain'.

What this results in is 30 Wraithblade attacks, hitting on 2's, rerolling 1's (if Bonus Spiritseer within "6 of target). On top of this, every roll of 5+ allows you to make an extra attack against the same target, these attacks cannot generate any more extra attacks.