I decided to give a little backstory to my phase 4 sprite. (In the comments)

In phase 4, Sans regains consciousness after being possessed by Gaster in phase 3. Gaster is doing everything in his power to keep Sans alive and kill the human until they reset. Seeing as the human is still alive, Sans really pulls the gloves off. His attacks are completely random, there's no such thing as patterns anymore, you never know what he's going to do next.

well then R.I.P the player

Well then the player is fricked