Oathkeeper

Equip {2}
Equipped creature gains +1/+1 and has vigilance.
Research 1 — {2} (Rather than cast this card from
your hand, you may pay {2} and exile it with one
time counter on it. At the beginning of your upkeep,
remove a time counter. When the last is removed, cast
it without paying its mana cost, and when it enters the battlefield, you get a research counter.)