During its normal mode, Mask Change moves diagonally, only changing direction when it touches an outer wall, and only turning in clockwise directions. It passes over blocks and eliminates bombs caught in its path. Collision with the boss at any time will damage the player.
The boss will sometimes pause, wink, and release a heart, which floats toward the player. The heart itself is not harmful, but if one is destroyed by a bomb blast, the boss will become enraged and will directly seek the player for a short time.
The boss may also wink and release eight sparks, which spread out and move in straight lines until they exit the screen. This attack can damage the player.
When Mask Change is destroyed, the victory music does not play.