Pouncing Shoreshark - [Showcase] The List (PLIST) Board Game Whenever a creature token enters

Whenever a creature token enters the battlefield under your control

Cascade (When you cast this spell

Destroy up to two target artifacts and/or enchantments

This is the Atarka Spindown Life Counter from the Dragons of Tarkir set

devouring both flesh and stone

Pouncing Shoreshark - [Showcase] The List (PLIST) Board Game Whenever a creature token entersMutate {3}{U} (If you cast this spell for its mutate cost, put it over or under target non Human creature you own. They mutate into the creature on top plus all abilities from under it.) Flash Whenever this creature mutates, you may return target creature an opponent controls to its owner's hand.