Knowledge Pool is a rare Artifact card from Mirrodin Besieged (MBS), collector number 111. Current market price: $1.20 (foil $7.49), TCGplayer market prices via Scryfall.
Imprint — When this artifact enters, each player exiles the top three cards of their library. Whenever a player casts a spell from their hand, that player exiles it. If the player does, they may cast a spell from among other cards exiled with this artifact without paying its mana cost.