Mana Burn

Whenever mana empties from a player's mana pool, Mana Burn deals that much damage to
that player.
At the beginning of each player's end step, tap all untapped lands that player controls. Mana Burn deals that much damage to that player
"You shall consume all your mana, or else
mana will consume you"
. - Mizzix of the Izzmagus