Liege of the Hollows

When this creature dies, each player may pay any amount of mana. Then each player creates a number of 1/1 green Squirrel creature tokens equal to the amount of mana they paid this way.

Thalia and The Gitrog Monster

First strike, deathtouch
You may play an additional land on each of your turns.
Creatures and nonbasic lands your opponents control enter tapped.
Whenever Thalia and The Gitrog Monster attacks, sacrifice a creature or land, then draw a card.

Adarkar Valkyrie

Flying, vigilance
{T}: When target creature other than this creature dies this turn, return that card to the battlefield under your control.