First appears on the 3rd Underyard, and does masive damage to any hostile monsters around it. (Info only based on 3rd Underyard)
Mostly weak monsters like finks,Bolt,and pokeys will be destroyed in one hit, so stonger monster such as Crabatrons or Daves is recomanded,still it can kill in two hit like Zagnoid and Spurtz so use stronger monsters.
NOTE:It can't hit a digging monster in the underground like Valgos,Wormzer, and King Wormzer. It can be build in both the backyard and the Inferno, but it always costs inferno resources.