Rexx

 Rexx is a very dangerous boss found in Nether Fortresses. The Player must defeat Blue Thunder before they are able to challenge him.

No cutscenes play when The Player challenges Rexx, but lightning strikes his spawn point, setting off a momentary fire, then Rexx appears. He has the same behavior pattern as a regular Wither, however his Wither Skulls are shot out twice as fast and cast the Scourge effect. When a mob has Scourge, EVERY nearby mob within a range of 100 blocks immediatly turns hostile and attacks the Player for 40 seconds, which is what makes Rexx so dangerous. When killed, he drops 200 XP, several Nether Stars, and a Scourge's Bone Collar.