His name was Erosion/Elma, it will fits him before it suppose to, y'know?

A few curiosities:

His body went black and his eye sockets, nose and teeth went white and purple (as you probably noticed that.)

Some tips about his personality is that he's very mysterious, he usually sees and talks very nonchalantly clever, but when he does he says those wingdings, but don't be rude on that.

He's also serious and exquisite as his missions, when it is missions to turn into one with the followers, his victims are consumed by the void and static.

In the battle, he's very radical and torture, like he would use his Bone-sarigama (Bone is also fused with Kusarigama) as a weapon, whipping and slicing in half and turn into one, he is flawless with his sickle, never misses his victims.

This also might be overpowered than Epic Gaster or any Gaster's combined he come across, he can vaporized as he wanted.

He has 1 weapon, but with full power.

Powers we can say is, all the powers in the same as Last Breath and Cross.

He can create any kind of or weapon to use his knowledge, bones, magics, gaster blasters, Gaster's hands and special attacks cuz he's a Sans until Gaster possesses him but he's not even a Sans (he has 1, 100, but many of them as Normal Last Breath.)

He can do expirementing without failures to some to cause something new.

He can use his telekinesis, teleport, blue soul ability and flip the screen diagonal.

He has no Chara here, they vaporized into the existence, but he has a Gaster and his followers was no longer forgotten, but I was too lazy to draw something.