W.D. Gaster

At the beginning of your upkeep, create a 1/1 Construct creature token with vigilance and haste and “Sacrifice this creature, put a charge counter on each creature you control named W.D. Gaster”
{e}{e}{e}{e}{e}{e}{t} Destroy all creatures an opponent controls.

No one knows where Gaster went. They only know what he left behind.