Hearthpwn

Going for combo essentially means "ignore the opponent's board entirely and just worry about drawing your combo pieces while throwing burn at their face if you don't have the mana to kill them all at once". This is done often in decks where your opponent can amass a really huge board and can easily deal with your Doomsayer (like Shamans with their Thing from Below). At this point, all you really can do is play out your Coldlights and other draws, Ice Block their damage and try to kill them with what you have. Where you need to save up all your damage to bundle it in one turn, I've specifically mentioned as "go for the OTK".

Sorry for the late reply, I don't use this site very often.

have u tried it?

Yes of course, I created the list. 

how is it going with this deck in today meta?

To be honest with you, it's not at all good in today's Standard meta. You lose very easily if the board is flooded with decent size minions (Shaman, Hunter), or if the opponent has too much health (Warriors, Druids). All of these classes are very much present on ladder leaving you with only Warlock as your good matchup with a common deck.

The deck base has a lot of potential, but it needs new supporting cards, not just a friendly meta to be competitive. Some stuff that would help are unconditional board clears, some solid draw, and a few good healing spells for sustain. All three of these would help this deck in surviving and drawing the combo pieces.

If you want a more competitive version of an OTK Priest, I suggest sticking to Acolyte of Pain, Loot Hoarder, and Novice Engineer as your card draw, rather than Gadgetzan and Resurrect. Here's Neviilz' Velen Priest on Manacrystals.

The deck could be great in the future, but it'll take the Hearthstone Card Designers' help to get there. When all the cards of the upcoming expansion are announced, I'll update the list with the new spells should they prove worthy enough to be played. If some prove strong enough, they just might push the deck into competitiveness.

As of now, I suggest playing the deck for the fun of it without worrying too much on making it work competitively.

Hm very nice, more spell-oriented but that could be a great thing depending on the meta.

Possessed Villager might be better substituted for Flame Imp for the stat bonus if there's little aggro around, which may be the case considering all the slow and Taunt cards pushed into the Standard set.

It might be a good idea to include Darkshire Librarian in the Standard list. The average card quality is worse so you're more pressured to draw into Renounce early and Librarian cycles well. No net loss of card advantage and 3/2 for 2 contests the board well. It sucks a bit if you discard one of your 5-cost Neutral minions, but the benefit will usually outweigh that downside, and discarding one of the Warlock cards isn't that big a deal.

Adapting the deck to Standard is a bit tricky since you lose out on so many solid neutrals, just look at what's left after taking out all the Wild cards: Imgur.

Without knowing every Old Gods card, it's difficult to tell how the deck will look simply because there's a notable lack of cards when trying to build it.

One thing you can do though is try to replace the natural midrange synergy with a dragon one. This does change the function of the deck a bit though. Instead of competing for the earlygame, the Warlock tools are mainly used to survive against aggro and go par for par with control decks. Then Renounce Darkness would serve as a tool to eliminate your earlygame cards in midrange and control matchups. A bit less RNG with such a deck, a bit more dust cost, but a similar principle. I've tried theorycrafting such a deck: here.

Despite the name, it's a lot harder to predict how a new card would do in Standard, in that it is the more wild format.

Could work for sure, but I do fear that with both Wrathguard and Flame Imp you'll be wishing for health in the mid/lategame, especially against aggro. A Healbot could help in that case, but Healbot is a really debatable inclusion. I also thought about throwing in Mistress of Pain too, I feel like that can work about as well as Wrathguard in securing the earlygame and save you a bit of health.

I'm sure the Warlock cheap minion slots are pretty flexible though; ideally you won't need to play the class cards past turn 6 or so.