It's a little different in 40k, psyker powers tend to be really strong with major drawbacks like killing everyone in the world. The later RPGs mitigate this with fettered casting that lowers the effects but prevents perils of the warp cause it turns out a small chance of catastrophe works in a non-persistent wargame but in an RPG it just turns your character into a timebomb.
I built a psyker character entirely defensively, he's basically made of healing. With an repertoire of eight Minor Powers, only one can be called offensive - Weaken The Veil. Dark Heresy veterans probably know this as a game-destroying power, because it causes Psychic Phenomena to manifest thrice as easily.
I took Weaken The Veil precisely for its potential comedy value, but I already roll a preposterous amount of 9's on my power dice, so I've only pulled out this power once. The party was ambushed by five psyker cultists inside an apartment flat. Sensing the perfect opportunity, I tore open the Empyrean on the hope that they would obliterate themselves. All five of them wound up summoning Phenomena, and then some.
The best was the guy who the GM had already lined up to use Precognition. He advanced to Psychic Perils and straight up detonated, meaning the last couple seconds of his life was just the words "YOU ARE BONED". Thanks to a literal reading of the effects table, by the end the round after The Weakening we went from a fairly orderly shootout in an apartment, to dodging explosions and falling debris in the eye of a hurricane made of flaming blood. It was only by pure luck of the dice that nobody in the party died.
That was instance number four of six times (and counting) my flagrant misuse of psychic power rolls nearly ended the campaign.