Sans, Lazy Judge

Haste, triple strike, trample, vigilance, reach
Sans cannot attack or block unless you have at least 10 creatures in your graveyard and/or exiled.
Damage dealt by Sans cannot be prevented.
When Sans becomes the target of a spell or ability, you may pay {r}. If you do, that spell or ability no longer targets Sans.
When Sans takes damage, you may pay {w}. If you do, prevent that damage.
When Sans would leave the battlefield, you may pay {b}. If you do, Sans does not leave the battlefield.