Anti-Mage

Flash, haste.

Mana Burn - Whenever Anti-Mage deals combat damage to a player, put a +1/+1 counter on this creature, and target tapped land that player controls does not untap at the beginning of their
next untap step.

Mana Void - {4}{b}, {t}: Anti-Mage deals X damage to target player, where X is the number of tapped lands they control.