Megalovania

It's just regular Megalovania. Except that Sans doesn't take a break after his final attack and he attacks Frisk/Chara before they could fight or spare him. I'm to lazy to write an essay now. By The Way, We Have Megalovania At Home started with this song This song has an animation, while the other songs don't

Song 9 of Undertale Genocide Package

Sans: Steel aka 0chromat Chorus BaritoneBlur aka Scott Orenstein Steel Sym Tom Previte aka Tenebrismo Uprising Attorney

Mix By Steel Art By Steel Animation By Upgraded Moon Productions Flashback Art By PrinceesKeda and Sym