Ape

Token Upgrade
If upgraded with a Pet Token, Ape will use his first action in dungeons to transform into super Ape. The transformation will last for class level / 5 actions, and gives a class level% boost to all stats and Ape will hit twice. This means at class level 100, Ape would have a 100% boost to all stats for 20 actions. This only works once per room/floor.

Recommendation
Ape could be Unlocked during a UPC while pets run item camps and level up, since the challenge require no rebirths for a long time.