We lost our last Tyranid player because of this change. He is now playing an Abomination (untouchable/pariah tier anti-psyker) named 'Shadow' in one of our RPG groups to went off his rage .
The Shadow In The Warp still helps.
It doesn't prevent psychic powers being cast, but it does mean that if someone does trigger perils of the warp (and bear in mind that's generally going to happen more, because firstly people are flinging 3-6 dice in blobs rather making 2D6 tests and secondly daemonology powers trigger perils far, far more often), then because many of the results require leadership tests, he's going to be taking the worse results more often and the beneficial results far less.
Plus, tyranids tend to do better than most for psychic power available to shut things down. Tervigons generate warp charge as a troops choice, Zoanthropes are cheap and mastery level 2, and hive tyrants push out two warp charge but are far more dangerous than most other psykers (daemon princes/greater deamons aside).
Edited by Magnus Grendel, 23 June 2014 - 06:39 AM.