Legendary Planeswalker — Mordenkainen
+2 : Draw two cards, then put a card from your hand on the bottom of your library.
−2 : Create a blue Dog Illusion creature token with "This token's power and toughness are each equal to twice the number of cards in your hand."
−10 : Exchange your hand and library, then shuffle. You get an emblem with "You have no maximum hand size."
The power and toughness of the Dog Illusion token will change as the number of cards in your hand changes.