Story: You decide to go back to BeastSans1's regular home to finally kill The Glitch (Gaster), but it ends up being something else far more worse. Oh no. Phase 1: Invincibility Phase 2: The Demon In Himself Phase 3: Puppet BeastSans1 If you kill him (somehow), you will experience a great deal of PAIN.
Credit to whoever created music and soul sprite.