The Great Sandworm
Plantera
This mod is AWESOME. I think that the spawn rate for Manifestation of Pinky is to high though, especially since, in early game it can catch you off guard and is almost, if not as powerful as king slime but with a tiny hitbox
They only have a chance to spawn at the beggining of a new day after beating King Slime so I don't think that's to high of a spawn rate.