If you would draw a card while your library has no cards in it, you win the game instead. He’s not exactly expensive to drop, he’s only 2U. He is a 2/2 though, so it wouldn’t be surprising to go to win and get dismembered before you win the game and lose; it’s a hilarious win-condition, but I feel that disruption could catch up with him too fast.
Blue gets some ramp! Deranged Assistant for 1U gives you a 1/1 that can tap to mill yourself 1 and add 1 to your mana pool. Not as good as birds, which adds 1 of anyway, but one mana is always helpful. As a common, he isn’t bad.
Avacyn’s Pilgrim is basically a 1/1 green Plains. He gives us 1 white for his tap, and costs 1 green to play. I was hoping when they made something like this, he’d provide either green or white, not just white, but still, not a bad common.