Community

Thief of Sanity
Creature — Specter
Flying
Whenever this creature deals combat damage to a player, look at the top three cards of that player's library, exile one of them face down, then put the rest into their graveyard. You may cast that card for as long as it remains exiled, and mana of any type can be spent to cast that spell.
Rulings (5)
In a multiplayer game, if a player leaves the game, all cards that player owns leave as well. If you leave the game, any spells or permanents you control from Thief of Sanity's effect are exiled, and any of the face-down exiled cards remain face down indefinitely. No player may look at them.
Oct 5, 2018
Thief of Sanity's effect doesn't change when you can cast the exiled card. For example, if you exile a sorcery card, you can cast it only during your main phase when the stack is empty.
Oct 5, 2018
An effect that instructs you to "cast" a card doesn't allow you to play lands.
Oct 5, 2018
Legality
Formats by platform
Commander
Competitive
Digital
Community & retro
Printings (6)
OTC#243$0.84
Outlaws of Thunder Junction Commander
CLU#212$0.40
Ravnica: Clue Edition