Geistflame Reservoir 
Artifact
Whenever you cast an instant or sorcery spell, put a charge counter on this artifact.
, 
, Remove any number of charge counters from this artifact: It deals that much damage to any target.
, : Exile the top card of your library. You may play that card this turn.
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL