This is a variant of Praxis Midrange that swaps out mainstays Sandstorm Titan and Heart of the Vault both to make better use of flyers like Crimson Firemaw and Soulfire Drake. I designed this deck after losing several matches where a board stall kept me from attacking on the ground and by own Sandstorm Titan preventing me from attacking through the air.
From my experience, this deck has decent game against Chalice, and Tavrod decks. The prevalence of its creatures to have Charge or Warp give it some capacity to rebuild after Harsh Rule. It's weak against decks playing Sandstorm Titan (of course), so hold on to your Obliterates if you anticipate it. Aggressive decks are usually an even matchup, with it playing a little stronger against Skycrag and a little weaker against Stonescar and Rakano.
I don't have any pretensions about this deck, but it plays just differently enough from other Midrange Praxis decks that I think it has a niche. That niche is largely opponents not expecting Praxis to have this many charge flyers.
This deck isn't terribly more complicated than typical Midrange Praxis, but I've found it more reliant on maintaining tempo (hence the low Time Influence on cards, Dawnwalker excepted). Winning with this deck is largely reliant on getting your flyers down on curve (or faster if Initiate and Power Stone allow) and attacking over ground forces. Keep the heavy Fire Influence in mind when deciding which hands to mulligan.
Heavy lifters:
Soulfire Drake is MVP here, and most other creatures work favorably with it's entomb.
Crimson Firemaw is a great card that Charge makes better.
Pouncing Drake may be an average creature in most circumstances, but with Charge it's four points of evasive damage you can play from the top of your deck.
Diogo Málaga works from the other direction, instead of an evasive creature getting Charge, he's a Charge creature that gets evasion.
Support:
As most Praxis midrange decks, although without Temple Scribe (second Time influence often too harsh).
Other considerations:
Xenan Initiation is a little weaker in this deck than in normal Praxis Midrange because creatures tend to have lower health on average. Still a consideration simply because of Dawnwalker.
Marisen's Disciple is a versatile four drop that can either stop ground aggression with it's scorpion or augment your air forces with it's locust. I think it's a strong consideration for replacing Pouncing Drake, although it doesn't work nearly as well with Soulfire or Ageless Mentor's effects.
Xenan Obelisk has demonstrably proven itself a strong card in any Time deck, but it's a little weaker in this deck because it's off tempo. If you don't have flyers already in play, it's not much help, and if you do, you're likely already winning.
This deck could almost certainly be further optimized, but this as it currently stands as of October 10th.