A mod of some kind with the theme of "Eating enemies". When you crash into an enemy head on and destroy them, heal your hull based on their Max HP. Or perhaps a boost in regeneration instead (hell maybe a bit of both?).
Some draw backs could be increased size or something. Most likely would be a wild mod of some kind, or maybe a strong version of the idea be made into a super mod. If it's a super mod, another drawback to add would be a slowly ramping up in self damage "Starving" until you "eat" something. Then the amount of self damage resets.