Lemm, Relic Seeker

You may look at the top card of your library
any time.

You may play lands and cast artifact spells
from the top of your library.

{t}, Sacrifice an artifact: Search your library for
an artifact card with mana value equal to 1
plus the sacrificed artifact's mana value, put it
onto the battlefield, then shuffle. Activate only
as a sorcery.