When you unlock this door, manifest dread, then put two +1/+1 counters and a trample counter on that creature. (You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Whenever a creature you control deals combat damage to a player, turn that creature face up or put a +1/+1 counter on it. (You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)