Bowser's Castle (Mario + Rabbids Kingdom Battle)
From the Super Mario Wiki
The only part of the level features MegaDragonBowser as a boss, as well as a few Lava Valkyries as support. The second phase features some Pyroclasts as stage hazards as well as spawning Lava Bucklers, and the third phase spawns Lava Smashers.
Once MegaDragonBowser is defeated, Spawny is rescued, and the ending and credits play.