Renaissance

Blue Mana Battery

{2}, {T}: Put a charge counter on this artifact.
{T}, Remove any number of charge counters from this artifact: Add {U}, then add an additional {U} for each charge counter removed this way.

Fourth Edition Foreign Black Border

Fourth Edition

o2, oc
T: Put one charge counter on Blue Mana Battery.
oc
T: Add o
U to your mana pool and remove as many charge counters as you wish. For each charge counter removed from Blue Mana Battery, add o
U to your mana pool. Play this ability as an interrupt.

Legends

o2oc
T: Put one counter on Blue Mana Battery.
oc
T: Add o
U to your mana pool. Remove as many counters as you wish. For each counter removed add o
U to your mana pool. This ability is played as an interrupt.