Black Mana Battery 
Artifact
, 
: Put a charge counter on this artifact.
, Remove any number of charge counters from this artifact: Add 
, then add an additional for each charge counter removed this way.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL