Sans.

As an additional cost to cast Sans. exile 15 cards
from graveyards.
When Sans. enters the battlefield look
at the top 3 cards of target player's library.
At the beginning of your upkeep create
a colorless Gaster Blaster artifact token with "{t} Sacrifice Gaster Blaster: It deals 3 damage
to any target.".
Pay 3 life: exile Sans. Then return him to the battlefield under its owner's control.