Altar of the Lost 
Artifact
This artifact enters tapped.
: Add two mana in any combination of colors. Spend this mana only to cast spells with flashback from a graveyard.
Legality
standardNOT LEGALpioneerNOT LEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL