Tamiyo, Inquisitive Student #49

Flying Whenever Tamiyo, Inquisitive Student attacks, investigate. (Create a Clue token. It's an artifact with "2, Sacrifice this artifact: Draw a card.") When you draw your third card in a turn, exile Tamiyo, then return her to the battlefield transformed under her owner's control.

[+2]: Until your next turn, whenever a creature attacks you or a planeswalker you control, it gets -1/-0 until end of turn. [-3]: Return target instant or sorcery card from your graveyard to your hand. If it's a green card, add one mana of any color. [-7]: Draw cards equal to half the number of cards in your library, rounded up. You get an emblem with "You have no maximum hand size."