Nature's Will

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.

"The troll took the fauns' hesitation as fear and roared in triumph. In truth, they'd seen the ledge begin to crack beneath his weight."
—*The Goose Mother and Other Tales*

Wilds of Eldraine: Enchanting Tales

The frogs' friendship wasn't necessary for survival, but it did come with generous servings of strawberry crumble.

Secret Lair Drop

"Without the kami to speak to nature on our behalf, we must beg help from nature directly."
—Seshiro the Anointed

Champions of Kamigawa

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.