Unbending Tenacity

Enchant creature card in a graveyard
Put enchanted creature card onto the battlefield tapped under your control and attach this
to it. When this leaves the battlefield, enchanted creature's controller sacrifices it.
Enchanted creature gets +1/+1 and doesn't untap during its controller's untap step.

At the beginning of the upkeep of enchanted creature's controller, that player may pay {1}{b}. If
the player does, untap that creature.