Sans is a deformed creature and the most horrific Sans in this AU like everybody else in this Underworld. Sans's eyes both glow left is orange while right is blue, plus he has split skull where energy pours out.
If you see him, you're dead. If you Shake his hand, you're dead. He is a true monster.
He's commonly seen with moldy green bones and yellow teeth. His pupils are orange and blue, and his skull is cracked (which leaks orange and blue light/smoke). He is very large, and he appears to have a hunched back.
He is 3 times the size of the original Sans, and he has a dropped jaw with enormous teeth.
He wears an outfit similar to his Undertale counterpart, only without shoes.
Frisk/The Player resetted too many times/hacked the game files, therefore causing all of the monsters to turn into amalgamated, horrifying creatures that are dead-set on killing Frisk.