You were put into a match against a Player using Negatale Sans. You were teleported into the Last Corridor of Negatale Sans, which, to be honest, was not much different from the original Last Corridor other than just being blue. Negatale Sans was at the end of the corridor, and you were at the beginning. You were on the Chara Team in this match, so it meant you had to kill him to win the match. In the background, "Waltz of Worry" was playing. (Here is the link to it if you wanna listen to it: https://soundcloud.com/utlc/waltz-of-worry). You have 300 seconds to kill him before the time runs out and it will be a draw. He has 200 stamina and only 1 HP, you have 92 HP with Real Knife that does 99 damage to enemies equipped, drain his stamina so he can no longer dodge and finish him off, go.