Hearthpwn

Surrender to Madness is much stronger when you have access to Emperor Thaurissan, since you naturally run a lot of draw but usually have serious mana issues. In particular, he allows you to have a much easier time casting it in the first place, especially alongside Mojomaster Zihi, as well as allowing you to continue to play a good amount of cards while you start to draw into buffed minions.

Priest also just generally has a lot of very good wild-only cards for minion-based decks, such as Velen's Chosen and many of the older dragon cards. There's also Echoing Ooze to take advantage of your buff spells, and Loatheb to buy you a turn against a large amount of decks.

Note: There's essentially only one reason to use this over a normal wild dragon priest, and that is: to win some games with Surrender to Madness, because it is an interesting card.