Crashing Wave (TLA 300)

Sorcery • Mana cost: {U}{U} • Avatar: The Last Airbender • Uncommon

As an additional cost to cast this spell, waterbend {X}. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)
Tap up to X target creatures, then distribute three stun counters among any number of tapped creatures your opponents control. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Illustrated by Claudiu-Antoniu Magherusan.