An unfortunate series of health problems prevented me from playing on launch, and I've just started putting my cards together into things that one might call decks.

Stuck Deathseer Thrall into an outdated Evolve shell. Seems to work well enough. The ability to single target "evolve" is actually quite useful if you're happy with most of your minions, Evolve being as random as it is. It can also function like the Priest hero power, since the transformed minion is at full health.

I think the key to Deathseer is that you might not want to play him on curve. As others have mentioned losing the base hero power can actually be detrimental to holding the board.

Funny that it took me this long to warm up to Evolve as a deck type. The sense of randomness and mystery is actually part of the charm.