Rule 106.13 · Mana

One card (Drain Power) causes one player to lose unspent mana and another to add “the mana lost this way.” (Note that these may be the same player.) This empties the former player’s mana pool and causes the mana emptied this way to be put into the latter player’s mana pool. Which permanents, spells, and/or abilities produced that mana are unchanged, as are any restrictions or additional effects associated with any of that mana.

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Ask the judge Pro

The life counter has an AI judge that answers your play citing the exact rules. It is part of Gatewatch Pro; the rules, Oracle text and rulings stay free.