In Deltarune , when K. Round loses all health, the battle ends because its crown falls off, not because it is defeated in the usual way.

What that means

  • K. Round is a special boss where ACTing is the key mechanic.
  • Its crown is the real objective of the fight; once the crown becomes 100% loose, it falls off and the encounter ends.
  • So “losing all health” effectively triggers the fight’s finish rather than a standard knockout animation.

Simple version

Think of it like this: you are not just draining HP — you are breaking the boss’s grip on its crown, and that ends the battle.