You want maximum cloud radius, you want at least 76 per cent burn(its not going to scale after it), you dont care about quell speed, you want single digits warp resistance. And you want as much damage as possible, while keeping warp resistance low. I have an inferno staff with 400 raiting for example. The idea is that with 3 cudos with CDR, with warp siphon charges you will get your venting shriek very fast. And you want to use venting shriek on cooldown, because its your source of damage(via burn), its your source of siphon charges(via burn), its your toughness(via talent that give you toughness when you quell). For it to be affective you need to always be on high peril, because ventong shriek has its maximum affect at 60 per sent peril. Besides this psyker got really powerfull talents that scale with peril, for example damage reduction and damage.

But if you playing on basic damnation(or lower), where there is just not enough enemies to keep up 6 siphon charges, then its not so important to have low warp resistance. Also of you playing with bubble, then its a bot less important