Castor, Cartographer of Dreams

Hexproof
Whenever Castor, Cartographer of Dreams,
enters the battlefield or attacks, create a colourless
Map artifact token with "Sacrifice this artifact:
search your library for a card, reveal it, and put
it into your hand. Then shuffle your library."
Whenever you reveal a noncreature, nonland card
from your hand or library, Castor gains flying
until end of turn.