Name:Bottomless Pool
ManaCost:U
Types:Enchantment Room
T:Mode$ UnlockDoor | ValidPlayer$ You | ValidCard$ Card.Self | ThisDoor$ True | Execute$ TrigReturn | TriggerDescription$ When you unlock this door, return up to one target creature to its owner's hand.
SVar:TrigReturn:DB$ ChangeZone | ValidTgts$ Creature | TargetMin$ 0 | TargetMax$ 1 | TgtPrompt$ Select up to one target creature | Origin$ Battlefield | Destination$ Hand
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, return up to one target creature to its owner's hand.

ALTERNATE

Name:Locker Room
ManaCost:4 U
Types:Enchantment Room
T:Mode$ DamageDoneOnce | CombatDamage$ True | ValidSource$ Creature.YouCtrl | TriggerZones$ Battlefield | ValidTarget$ Player | Execute$ TrigDraw | TriggerDescription$ Whenever one or more creatures you control deal combat damage to a player, draw a card.
SVar:TrigDraw:DB$ Draw
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.)\nWhenever one or more creatures you control deal combat damage to a player, draw a card.