Nature's Will
Enchantment
Whenever one or more creatures you control deal combat damage to a player, tap all lands that player controls and untap all lands you control.
Illustrated by
Wilds of Eldraine: Enchanting Tales#102RareEnglishLegality
Rulings
Dec 1, 2004
The lands are tapped and untapped once each time combat damage is dealt (usually once each turn, but first strike, double strike, and multiple combat phases can change that), not once for each creature that deals combat damage.