Spy Master Azriel

Flying, First Strike, Double Strike
•Whenever a creature enters the battlefield, you may give Spy Master Azriel +1/+1.
{b}{b},{t}:Sacrifice a number of creatures under your control. Give Spy Master Azriel +1/+1 for each creature sacrificed this way.
{t}:Search your library for a Legendary Creature and add it to your hand.