Name:Cramped Vents
ManaCost:3 B
Types:Enchantment Room
T:Mode$ UnlockDoor | ValidPlayer$ You | ValidCard$ Card.Self | ThisDoor$ True | Execute$ TrigDealDamage | TriggerDescription$ 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.
SVar:TrigDealDamage:DB$ DealDamage | ValidTgts$ Creature.OppCtrl | TgtPrompt$ Select target creature an opponent controls | NumDmg$ 6 | ExcessSVar$ Excess | SubAbility$ DBGainLife
SVar:DBGainLife:DB$ GainLife | Defined$ You | LifeAmount$ Excess
AlternateMode:Split
Oracle:(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.)\nWhen 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.

ALTERNATE

Name:Access Maze
ManaCost:5 B B
Types:Enchantment Room
S:Mode$ Continuous | Condition$ PlayerTurn | Affected$ Card.YouCtrl+nonLand | MayPlayLimit$ 1 | MayPlay$ True | MayPlayAltManaCost$ PayLife<ConvertedManaCost> | MayPlayDontGrantZonePermissions$ True | AffectedZone$ Hand | Description$ 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.
Oracle:(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.)\nOnce 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.