BC MUTATIONS

Okay, thing that came to mind re: Black Crusade mutation system.

The mutation system is balls (literally in the case of some gods) and contains numerous things that totally hose social characters and way too many choices that force your character to become some kinda of Deviantart furry OC.

A quick hack I've thought of is, at a corruption threshold, a player can roll infamy as usuall to try to roll on their gods table or, instead of the usual gift of the gods table:

The player chooses a trait as a mutation. If the trait has a numeric (X) value, that value is equal to the natural attribute bonus of his god's favored attribute. Unnatural Characteristics purchased as mutations only get half the attribute bonus (round up). Unaligned PCs select a attribute of their choice, but must use it for all future mutations as well.

Example, Nurgle Marine, with toughness 45 and Unnatural toughness 4 hits a mutation threshhold. He picks flying. Since his natural toughness bonus is 4 (he ignores the UnTou), he gains flyer 4, and works with the GM to describe how this mutation manifests/looks like (fly wings, assblasting off the ground like a perpetually farting hovercraft, turning into a giant pooballoon/sinister Blade Runner blimp, whatever)

This also allows PCs to remain relatively "normal" looking if they want to, so you can have your shoeless River Tam equivalent infiltrate imperial society while making people's heads explode with her Unnatural Strength 6 feet.

This also allows for Size 1 chaos space marines.