Change regen to FNP
Why not change catalyt to- FNP but if given to a unit with FNP it gains the current regen rule.
You could also create something where as biomatter is devoured the unit gains stat improvements based on their IB type. So similar to dark elves but based on model count (with bulky counting as 2, very bulky as 3)
Also spore launchers, where the unit forgoes shooting to cloud the air with spores stopping all overwatch from models within 6 inches of where they are as spores clog gun barrels.