Rainbow sphere, a monster that appears and behaves as if it were any other type of sphere with an exploding attack, but it does not die when it explodes; it becomes a different, random sphere type. There are two possibilities for how it can be killed: it could be brought down to 0 HP like normal, or it could have a limited number of incarnations, after the last of which it explodes and dies normally.

Internally, it should use newcham to handle its transformations; possibly it could be implemeted as a shapechanger capable of turning into any explodable e monster.