Locked Cupboard

As an additional cost to cast Locked Cupboard, exile up to 3 artifact cards from your hand.
Locked Cupboard enters the battlefield with a lock counter on it.
{t}, {1}: Remove a lock counter from Locked Cupboard
{t}, {2}: If there are no lock counters on Locked Cupboard, you may cast a card exiled with Locked Cupboard without paying its mana cost.