Reznor is a mini-boss found in world 1 till 3 fortress. there are four in the room on spinning platforms the first world ones has a billy gun from SMBX so you can shoot them or you can jump under them after 2 are hit the ground will vanish one by one. they will attack the heros by shooting fireballs at them. there are 2 new ones which are bloom and tecna versions.

World 1: Black Yoshi Egg

World 2: Brown Yoshi Egg

World 3: Cyan Yoshi Egg

World 4: ?