Thought Prison
Mana cost
Mana value5TypeArtifact
Color identity
Colorless
RarityUncommon
SetMirrodin (MRD)
ArtistGlen Angus
Price€0.08 · foil €0.44 · $0.20
Thought Prison 
Artifact
Imprint — When this artifact enters, you may have target player reveal their hand. If you do, choose a nonland card from it and exile that card.
Whenever a player casts a spell that shares a color or mana value with the exiled card, this artifact deals 2 damage to that player.
Whenever a player casts a spell that shares a color or mana value with the exiled card, this artifact deals 2 damage to that player.
Legality
CommanderLegalStandardNot legalPioneerNot legalModernLegalLegacyLegalVintageLegalPauperNot legalBrawlNot legalOathbreakerLegalHistoricNot legalTimelessNot legalPenny DreadfulNot legal
Rulings
2004-12-01
The second ability triggers only once per spell. If the spell shares both a color and a mana value with the imprinted card, Thought Prison deals 2 damage, not 4.