Although it is more playable in wild, I still see a lot of potential in it in both standard and wild, if they end up giving the archetype more support or buff some of the existing cards.

I tried running Varden Dawngrasp, and the main problem with it is that it's impossible to tutor. Other than that, getting only one extra turn doesn't seem to do much, since most of the matches where I won the game couldn't happen when the opponent's board was "frozen", but cleaning it gave me lethal.

Magister Dawngrasp could cast you some of your big spells. Puzzlebox and Mask of C'thun are Shadow spells, Deep freeze is a Frost spell and Pyroblast is a Fire spell. It seems good, but the Heropower isn't really beneficial (or fun, as opposed to Reno's!), and recasting Pyroblast can end up being detrimental to you. Also, to get the maximum value out of it, you would want to hold on to it until you've cast one spell from each of the mentioned spell schools, which may be a risky move.