Elmo, the Infinity-Spire

Trample, haste
Whenever Elmo deals 3 or more combat damage
to an opponent that controls one or more
creatures, each opponent discards a card, mills a
card, sacrifices a creature, and creates a Treasure
token.
Elmo's World—Whenever an opponent sacrifices
an artifact, Elmo gets +0/+2 until end of turn.