This season, I played exclusively versions of this deck as a response to Primal + Shadow (+ Fire sometimes) lists being popular, and people saying that
Omniscience was broken. There were also enough decklists that sat back and played removal that having a low-unit deck made sense.
As the season went on, I saw less representation of those decks, but this was still enough to get me to D1.
Gameplan
Depending on the matchup, either we are spending our spells 1-for-1 with the opponent's units, and getting card-advantage from them holding dead-ish removal in hand. Or we are going face with our damage and then topping out with cards that hit for 5+ in the late game to close things out. How to spend your cards and when to transition to going face is matchup and draw dependent and takes experience to get right.
You can do fun stuff, like this:
Tips
It's okay to not spend your power on early rounds even if you could remove something with
Ignite so you can get better value from a better target, get
Winter Tomb on-line instead, or have targets for your more expensive
Liquid Flame that you want to play on 3.
For
Ossuar Longbow, it's tricky to know whether you want a clear board to be hitting with it, using
Winter Tomb to get value per turn (Which means you can't hit face with longbow), or slapping it on an early
Mouth of the Hermit which can take over games fast.
Winter Tomb and
Warding Beacon are great at hitting the opponent's Aegis. Just don't forget that hunt (From
Mouth of the Hermit and
Ossuar Longbow) will get blocked by their Aegis.
Keep in mind that even if they've been holding removal all game and you drop a
Parapet Sentry that they get to remove on their turn, it still means their losing tempo and not spending all of their power on something else. It also gets you value on summon.
Careful,
Winter Tomb on a unit with Lifesteal will deal 0 damage!
Clash of Wills is obviously nuts the turn after they play
Omniscience, dealing 12 damage and refilling your hand, but it's also generally pretty good. Something to understand about card advantage is that in the most extreme mental-model, you just take your full deck and have it in your hand. In that case, you have access to every card, but you're still gated on how much power you have. And because the game is ending in a turn or 2 in either case, it is much less of a big deal to give both players 3 cards than you might think. That said, it makes it likely they'll draw counters to your spells, so plan to be using multiple spells in a turn or relics to close out the game.
In general, consistent life-gain or swarm is hard for this deck.
Matchups
These are loosely from easy to hard:
mono-Shadow - They play a lot of removal that is dead, there are times I won't play
Parapet Sentry just to play around
Abhorrent Revival. It's super easy to 1-for-1 and then burn face to win.
mono-Primal - Again so few of their cards are relevant, you can 1-for-1 most of it and get great value off of
Ossuar Longbow,
Flash Fire, and
Clash of Wills.
Primal + Shadow - Most of their gameplan is to draw a bunch and play removal, and then have really strong units with Aegis close out the late-game.
Tenacious Heron can be killed by weapons or
Winter Tomb which helps us keep their Aegis off,
Fallen Winter can either be ignored because they're so low you can go face, or throw
Winter Tomb on him. Be aware of when they have power open to counter our spells, and play units/relics accordingly.
Hermit piles - Similar to the above, but
Futility will 1-for-1 against us if they know to use it. Try not to play units into
Severin, the Hermit, because they both give so much value or damage if they're removed.
Fury + Justice aggro - It's easy to 1-for-1 their threats, you can deal damage to knock off Relic Weapons, but
Foxfang Katars is nasty, and they don't really have dead cards so it feels pretty draw dependent.
Veena - It's hardish because of their life-gain, but their units are pretty easy to remove. Be sure to handle
Tinker Overseer on your turn before it becomes a 5/5. Sometimes
Veena's Masterpiece strengthens their units such that you can't 1-for-1 and they're drawing cards, and most of their cards aren't dead which can grind you out pretty quickly.
Primal + Justice hunt - I found this matchup a bit hard: their cards are all proactive or counterspells. Many have static abilities that keep giving them value through
Winter Tomb (Such as
Olos, Elder Ranger and
Quinn, Beast Heart. They can get Lifesteal, some of their units have Aegis, and they can get armor. The best chance is to remove units as fast as you can, so they won't have targets to copy with
Mirror Image.
Ziat's Triumph - These are hard because they can gain life and be out of reach, and kill us quickly in the late game. They do have lots of removal cards that are dead, and don't have much card-draw. So as much as you can go face and get recurring damage off of weapons, the better. Often
Lystia, Flighty Mistral comes down and walls out your attacking damage, or
Winter Tomb is incredibly strong against her and they end up spending removal on their own unit.
Fire + Justice aggro - I'm not sure I've won this ever, their recruit off of
Calm Instructor means that pretty early on they are up 1 unit over what you can remove.
Mouth of the Hermit is a great blocker. I've tried
Heavy Hail for this matchup but our deck ideally just runs single-Primal cards.
Card Choices
You could play this deck with more Primal to play things like
Icy Scrying (Another way to deal with Aegis),
Lipa, Witch of the Woods (We don't have great 3-drops), and
Heavy Hail (Wins swarm matchups). That would probably be a better deck, and only means sacrificing
Flash Fire trolling.
I've tried playing
Caravan Delivery, but there aren't great Fire tech cards to use in your Market. In the matchups where I care about tempo, I think I just want to not be spending the extra 2 power.
I ran more
Urn of Choking Embers to tech for PS decks, but it at best relevantly hits 2 (Not counting something I hit but don't interact with). There are PJ matchups where EVERYTHING has Aegis and I miss having more of the Urn, but it's such a loss to either be a card down in 1-for-1 or lacking damage when I need it.