[@Punished Homura]
The full force of the C'Tan, perhaps. But currently, only 4 of them are believed to have survived. They probably did this to mirror the Chaos Gods. But still. The Outsider, the Void Dragon, the Deceiver, and the Nightbringer. And of those, only the Outsider and the Void Dragon are believed to exist in one piece, the others are shattered and spread across the galaxy. And of those two, only the Outsider is free, and he's completely batshit.

And even pre-nerf, the Tyranid would probably still beat em. I mean really. Fleets multiple times the size of the galaxy? That's insane.