Just wanted to share this grindy control priest I've been enjoying at Gold 5. 

This deck is always the control deck, and our win condition is usually exclusively fatigue. Something I noticed is that most other lategame decks tend to have a maximum of 3 really strong boards. Galakrond Warlock, for example, has 3 boards - their Galakrond, Zephrys and Dragonqueen. Resurrect Priest has slightly less than 3 boards - 2 mass resurrections and Catrina Muerte. Quest Druid is probably the deck with the most boards, between Cenarius, Zephrys, Dragonqueen and however many boards Ysera gives out, but is still manageable.

Because of this cap on 3 boards, this deck aims to run 3 board clears - 2 Plagues and 1 Shadow Word Ruin. Since Priest has basically 0 draw, in order to make drawing these boards consistent, we run the dragon package with Cleric of Scales to tutor for the answers we need. Against fast decks look for Breath and Penance, against slow decks hold the Cleric to gaurantee one of the clears.

Because Galakrond is so powerful as a value engine, we can afford to run a bunch of smaller minions like Twighlight Drake to fight for board early. 

Cobalt Spellkin is also an interesting inclusion - almost all of the current Priest 1 cost spells are pretty good, with the new Renew and other general utility cards like Holy Smite and Emblaming Ritual. Even Radiance is non-terrible in certain situations. 

The biggest weakness for this deck is Combo. To try to counter the Demon Hunter Combo, make sure to keep your health total high. Due to their silence, trying to wall up is mostly unsuccessful, but it's winnable since their damage output is limited to around 24, so look for your lifesteal cards off Cleric and try to use Spellkin for healing spells. If you're hitting lots of memer Hunters with King Krush OTKs, tech Kartut or something, but that's less important.