One of the best Priest cards in The Witchwood is Coffin Crasher, a minion that summons another Deathrattle minion from your hand after it dies. It teams well with such cards as Bone Drake, Tortollan Shellraiser, and itself.
The dragon synergies also work well in this low-cost deck with the help of such cards as Duskbreaker, Twilight Drake, Cobalt Scalebane, and Nightscale Matriarch.
The latter one also synergizes with the new healing spell -- Divine Hymn. In the late game, you can start pushing for higher damage with spells like Free From Amber and Mind Control.