You know these. They're from Azumanga Daioh.

This is a Cat creature, another major creature type in the 4chan set. They're very characteristic, and span over all five colors, although mainly green. Some of them are anime creatures, others are ordinary ones. Wait - what's the difference? Well anime cards work just like their ordinary counterparts, although anime sorceries, instants and enchantments may have creature types. Anime itself is not a creature type. Neither is another, basicly identical card type: meme. There are also anime meme cards, which work as either or both.

Sooo this is Piranha Cats. It has two new key abilities, Empowerment and Pack.

Empowerment is an ability that makes cards cheaper to play if you use the right mana. Piranha Cats' empowerment makes it ideal in a monogreen Cat deck as a trampling 3/3 for three mana, while not making it too useless in multicolored decks. The ability plays a major role in deck construction. Also, cards aren't necessarily empowered by the color it is. There are cards that, for example, misplace color-specific functions for a high original price (for example red counterers, bouncers and draws, empowered by blue).

The other ability this card presents is Pack. The explaination text on the card should fill you in. As you may guess, Desu use this ability more than any other creature type to gain bonuses.

... The picture is so adorable...