This simple mod makes mobs more willing to fight each other. It makes any mob able to willing to attempt revenge when attacked as well as making all mobs on a team attack other that aren't on the same team.
This can be disabled by a gamerule (mobFightUtils/enabled) when necessary.
Sadly, because some mobs use the more complicated brain system for ai, this mod won't work on them. The notable ones are the goat,