So, I've been GM'ing a game almost since the day Black Crusade came out, we went through a bunch of stuff before hand of corruption came out, then ran through that with the same party. Effectively all of the characters should really be spawn and/or ascended at this point and beyond the normal scope of play. BUT everyone wants to keep playing from a perspective of "well, we just accomplished this great feat, have a planet of our own to command, and want to be gods".

So, the supplement "tome" books have been pretty useful so far, but I wanted to get some addtional input from you guys on how to approach this. Infamy allows an excessive number of rerolls at this point and feels like it may need reworking, but at the same time such characters should remain powerful. On top of that, while these characters are very powerful, they aren't all Commanders and need some way to remain relevant at the head of an army.

Any thoughts? Currently the party consists of a human psyker with lots of exalted psychic powers, a Chosen Berzerker, a Champion (very commander-ish), and a Heretek.

An army needs far more than commanders. A military campaign can only be as good as its logistics, intelligence, and quality of equipment. The psyker and Heretek should find plenty to do here. As for the Berserker, beyond being an ideal shock trooper, I can't really say without knowing how far he is descended into bloody lust and madness... If he has no talent or interest beyond combat, well... If he has, he should find himself a purpose.

As for the general feel of the game, let the characters be powerful. And put powerful enemies in their paths. Enemies powerful enough that they can't just count on brute force and rerolls to take them down. This can be achieved several ways: daemon princes, secret cults, the inquisition, spess mahreens, etc...

Basically, let them have all the power they want. Then give them problems which their power alone cannot solve.