DSC-17 Access Maze

When you unlock this door, this Room deals 6 damage to target creature an opponent controls. You gain life equal to the excess damage dealt this way.
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Once during each of your turns, you may cast a spell from your hand by paying life equal to its mana value rather than paying its mana cost.
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(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.)