To mirror the Amonhket new card discussion, here's a thread for HOU discussion for Frontier. The first three cards have been leaked, those being:
Bontu's Last Reckoning
It's very unusual to see a Wrath effect at 3CMC even if the downside is important. As has been mentioned on other Frontier discussion channels (Reddit, Discord, Facebook), this card could work well next to As Foretold. It is also great with cheap Planeswalkers like Liliana of the Last Hope or Jace, Vryn's Prodigy. Mana rocks are another thing that could make this card work but the only alright 2CMC mana rock is Corrupted Grafstone. Wrath effects are great with Vehicles and coincidentally, Heart of Kiran is a Vehicle that works well with Planeswalkers. This is mostly just ideas being thrown around with so many directions but there might be something worth exploring here.
Samut, the Tested
I feel like Samut falls into the category of 4CMC Planeswalkers that just don't do enough. Her abilities are incoherent and each of them would want her to be in a different deck. Her first ability doesn't create card advantage and needs an aggressive creature-based deck to be worth it. Her second ability is solid, 2 damage divided is a great way to kill pesky creatures and finish off Planeswalkers. -2 Loyalty is a serious cost though, it only leaves her with 2 loyalty after using it and let's not forget that creatures in Frontier tend to have more than 2 toughness. Her ultimate is of course amazing and is reminiscent of Nahiri, the Harbinger's but the first 2 abilities aren't good enough to warrant including her in a deck that would for example want to fetch Emrakul.
Nicol Bolas, God-Pharaoh
This version of Nicol Bolas is very potent for 7 mana. His first ability generates card advantage from your opponent's deck while growing his Loyalty high enough to survive opposing attacks. His second ability wrecks opponents' hands at a pace that is hard to keep up with. It's great to have a choice between these two abilities in the first place. His third, -4, ability allows you to remove most large threats while also offering a possibility to finish off Planeswalkers or opponents. His ultimate is a one-sided board wipe, it takes quite a while to get there though, you can only activate it on his fourth turn in play (7+2+2+2-12). Nicol Bolas's biggest problem will be finding a fitting deck - Aetherworks Marvel probably doesn't want him as that deck usually needs to play green and colored mana is an issue here. Ugin is also just a better Planeswalker in this case because he can wipe the board right away. RG Ramp would also prefer Ugin or Hornet Queen/Dragonlord Atarka. Maybe we'll see some form of a tapout Grixis Control that will get to 7 mana often enough. I doubt it though, those decks would still rather play the Torrential Gearhulk+Dig Through Time package.
The problem with Hour of Devastation is that they went so weak on answer cards that unless it hits a very specific and prolific target, I can't see anything but sideboard play for them. Fatal Push has been the best card to enter the pool as far as answers go right now as it is easy to trigger via the fetches and hits a lot of targets. I do agree I really like Liliana's Defeat, if nothing else for at least a good answer against various black aggro strategies and maybe some mid-range ones. Unfortunately, it's not really much better than other extremely narrow hate cards of the past.
As for the "non-official" spoilers, Evaporating Melody being strictly better Dominate is also very interesting. Blue players getting good cards!
Checklands are also good to flesh out manabases.
That's Ixalan though, we'll have to wait a few months for those cards I do agree that Supreme Will is solid, having the options between countering and digging is such a great way to ensure you don't waste mana. It's even better next to Censor since your opponent will never know which one you have in hand.
Mirage Mirror is a "combo" with Ugin's Nexus because it can turn into Nexus, sac the original Nexus and by the time you start your next turn, there won't be a Nexus stopping you from taking an extra turn. Both of those cards go into a Metalwork Colossus shell, along with Sunset Pyramid as a new colorless card-drawing engine.
Hour of Revelation is a nice addition as an answer for Planeswalkers and engines. Not an autoinclude of course since it costs 6 mana.
I think for us Frontier players there are more playable cards coming from these sets than for the modern crowd. I am starting to wonder a bit about when Wizards will create their next non-rotating format and retire modern to the legacy status. Some of their experiments are starting to finally solidify and I definitely feel like modal spells from SoI block are better balanced than the ones from Kahns with the commands. Only reason I'm bringing it up here is because as frontier players we basically are buying into whatever that next official format may be right now. It's just a matter of what sets are in it when it comes about.
Wow, some of the new hate we're seeing here is incredible. Solemnity in particular I really like, since it shuts down both Marvel and Scales HARD, although the fact that it doesn't hate on Planeswalkers irks me. Crook of Condemnation I expect will definitely see play. While it's significantly more expensive than Tormod's Crypt, Crook is much more effective at hating on Emrakul and Delve, since you can simply exile cards as they go to the yard, rather than having to pre-emptively nuke the opponent's grave when you think a Dig or an Emrakul is coming. The land that nukes graves seems great, too. Putting hate on a land that works excellently on its own is incredibly versatile; it'll be a massive help against graveyard decks since it essentially allows you to be pre-boarded against them. I definitely want to try The Locust God in U/R Tutelage, too- a beefy, evasive, resilient body that spams blockers and evasive attackers when the deck just does its thing should be excellent- plus, it gives us an outlet for all of our draw spells when the Tutelage gets Lost Legacy'd away. I'm not sure about The Scorpion God's viability anywhere, though. It has a good body for its mana cost, but the activated ability is just a bit too expensive to be worth it. Plus, we don't have Persist in Frontier, which is really what it needs to be viable.
In general, HOU is looking not half bad so far. While it's lacking generic answers, the hate cards spoiled so far are exactly what Frontier needs; all we need now is Price of Progress or Blood Moon and Frontier can be a great format.