Hearthpwn

Depends on a lot of things actually. If the Warrior is smart, he'll pressure you on board, since you have a more than decent chance of beating him in Fatigue. If he pressures, The Coin might have to be used earlier.

Additionally, Shudderwock in Quest Shaman isn't thát good. It fills your hand with a lot of Lackeys, mostly, and even if it's able to conjure up multiple Former Champs' Battlecries, Warrior has access to near infinite removal.

Versus Warrior, but I play a full-on Control version of Quest Shaman, I usually just Shudder when it feels right to Shudder. We need to collectively stop seeing Shudder as a win-condition, but more as a value-generation card, to be used when it feels right.

Concluding, for me, doing a double Shudder rarely pays off holding off on using The Coin for so long. He'll just polute your hand with tons of Lackeys, and apart from a max of 12 damage through Lifedrinker, it's not worth the play.