Technically defined as a tool, the onyx sledgehammer is one of the highest tier melee weapons and deals bludgeoning type damage, for those days when you just want have a smashing good time. It is found in the tools section of inventory.
How to Obtain
It can be crafted or traded.
The onyx sledgehammer is useful when fighting small mobs. You can also use it to destroy turrets, and to take out flame geysers in hellish biomes. It cannot be used in PvP against other players.