Thaeriel, the former God of Light has fallen. On the bright side, he looks a lot cooler and he's a powerful 7 drop we can now play with! This article will cover his basic mechanics and then present a Control War deck meant to make the most of him. Technically, he probably works as well or better in Control Light, but I can't bring myself to make such an egregious lore violation!
How Does he Work?
Before we can build a deck around him, we need to understand how he works.
So for 7 mana we get noice stats and some delve options, but he doesn't refresh mana (like Sage of Renewal). So he's a bit slow. No blitz, frontline, or pro-active roar ability to impact the board immediately. Instead, he trades that tempo for value (3 cultists). This is important when thinking about where he might fit.
So what about his groupies?
You get to delve 3 times, and each time you see 3 different cultists. They can repeat between delves, but chances are good that you can find the one you need for the given situation. It's an incredibly flexible set of cards.
If you're ahead and need to seal the deal:
If you're behind:
What does this card remind you of?
Just like SiN, Thaeriel gives up tempo for value. You almost never see (saw) a control war deck running more than 1x sin, so Thaeriel is a natural substitute. Instead of 4 random creatures, 3 delves + a big body on board is a huge upgrade.
So now that we understand Thaeriel a bit better, let's take a look a Control War deck for him.
Lack of Wallet Control War
As with my Divine Coronet post, we'll take a look at an "I spend too much on video games" deck and a budget option. This one is the former.
Deck Code:
GU_1_6_BDyBDyKBbKBbKCyBEXBEXBHMKBcKBcKDSKDSLAFLAFDAFDAFCBCCBCCACCACCAXLALLALGBTIDrIDrBBqBBqLAMBFA
Control War is somewhat unique among control decks in that it almost never has a hand full of cards (hat tip to 
This deck also has lots of ways to make up for Thaeriel being slow. Pre-equipped relics can put in work on the turn you play him. After playing him, An End to War and/or your Cultists can make up for falling behind. Of course, you have to survive the turn. Leech from demos and heal from Magic Missle Launcher help keep our HP up.
The deck also has nasty combos like Demo + Sole Survivor and the critical Leviathan Hunter + Carnage Sweep for surprise clears.
Of course Blade of Whiteplains are included and along with Encumbered Looters give the deck a fair amount of card draw.
While I can't tell you from experience how this deck plays, I was able to find a very similar deck deck being run by Infinite Mana's Sifu. It's currently doing really well.
Vow of Champions is an unlikely add, but Martyr makes a lot of sense. The only thing better than Thaeriel is playing him twice. She probably works even better with Blades and Orcish Elites. Swapping out gleamweaver is fine, but with control light out there and running Pyramid Wardens, I think she deserves a 1x. (Of course whenever there is a disagreement between Sifu and myself, stick with Sifu.)
Budget Option
OK, so big surprise: a $2k+ deck does well. Can we reduce the price? Unfortunately, Thaeriel himself is an expensive card, so there's a high price on even a budget deck, but assuming you pulled Thaeriel from a leggy pack and are otherwise strapped for cash, can we build a budget deck around him?
Deck Code:
GU_1_6_BDyBDyKBbKBbKCyBHMKBcKBcKDSKDSGBMGBMCAZCAZLAFLAFCBCCBCCACCACCAXCAXIDgIDgCBAIDrIDrIBSIBSLAM
Thaeriel is $331 of the $384 price tag of that deck. You could swap Iron-Tooth Goblin out to reduce the price by another $7, but that's probably as low as you can go.
Losing Demos is a big deal of course. They are one of the best control cards in the game. War has no heal without MML and depends on leech, so we do our best to get some back in the deck:
Nokkvi is slow, but you have enough removal to clear board and then play her. Even if she gets traded, you will get some health back. Chimera's blitz makes it a better source of heal, and the blessed effect might let you find heal or some other utility in the sanctum.
We replace the stall component of demos with City Planners.
They add a lot of stats to the board and the two 1/4 frontlines can buy you time to play Thaeriel and survive the turn.
Don't expect 90% win rates with this deck, but it's viable.
Conclusion
Control Light is clearly the strongest control deck at the moment, so it's easy to slap any card in that shell, but we just can't have Fallen Thaeriel teaming up with Lysander. War makes so much more sense thematically, and Control War actually works really nicely with him.
Leave a comment and let me know if you see ways to improve the deck - particularly the budget version!