Tome of the Infinite 
Legendary Artifact
, 
: Conjure a random card from Tome of the Infinite's spellbook into your hand. It perpetually gains "You may spend mana as though it were mana of any color to cast this spell."
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyNOT LEGALvintageNOT LEGALcommanderNOT LEGAL