It says that you use it during the assault phase instead of assaulting (p. 40 C:WH). Page 52 of the BBB has the rules for Psychic powers, but it doesn't say that you can't use them in an assault. It sounds like you could use them in an assault although you wouldn't be able to make a close combat attack with that model. I would assume that initiative also comes into play so it might be possible to kill the psyker before he could use his power.
Puppet Dance sounds a lot tougher than the SM Fury of the Ancients. I'm suprised this hasn't come up sooner. Cursed chaos scum! The Emperor protects...
Puppet Dance sounds a lot tougher than the SM Fury of the Ancients. I'm suprised this hasn't come up sooner. Cursed chaos scum! The Emperor protects...