Animals rule in the Magic: The Gathering Bloomburrow set, with a new mechanic called Pawprint. Here's how it works and which MTG cards you'll find it on.
NEW Bloomburrow Skills – Expenses & Pawprints – Magic The Gathering
The new MTG Pawprint mechanic featured in the Standard-legal Bloomburrow set features multiple modal spells that you can play on a cycle of season cards.
Spend up to five Pawprints per seasonal spell. A modal option with three Pawprints can only be activated once. Pawprints are not a resource. They are not stored or carried over to the next turn. The first modal option costs one Pawprint, while the second costs two, and the third costs three.
The Pawprint mechanic is a unique twist on modal spells, but I don't think the cards will have a huge impact in the Standard format. Seasonal spells are added to some decks, but in small doses or only via the sideboard. In the Limited Blooburrow format, however, you have to be careful with these Mythic Rares, because they change the course of a game.