Dapling
Duke Fishron
These enemies would be perfect for adventure maps (especially the blazing wheel which would actually be really good for wiring mechanisms) so a way to summon them would be a blessing. There is currently no way to force them to appear, and they are always random, so it would be wonderful to have this. Perhaps the statues could only appear in the dungeon? The Spiky Balls could just connect to the nearest valid block instead of the statue itself.