Hi there! I was considering building a similar deck for standard, though I went on a slightly different axis than you. So, a lot of the red elementals feel like they want to be aggressive but many of them don't. Embercat and brawler are for much slower strategies (brawler doesn't have any haste or evasion and I don't feel it's playable in standard to be honest. And it's probably the same for embercat; it's mana production is just too limited even in an elemental/chandra themed deck. Unlike steamkin which can get very big, and ramp a lot at once with mana you can spend on any red card).

I also feel like mask of immolation isn't good enough. You're paying 2 mana for a 1/1 creature. Sure, it blocks, maybe even attacks, but once you sacrifice it you need to pay 2 mana to put it onto another creature. It's just not all that efficient, imo.

While Chandra Awakened Inferno is a powerful card, I believe it serves better as an anti-control finisher in slower decks. Reaching 6 mana on 20 lands, even for a 1-of card, is not all that likely. Leyline of combustion is decent, but I wonder if it would be better in the sideboard. It might also not be right for this deck since your opponents will be looking to sweep your board all at once rather than pick off individual creatures with targeted removal.

As for potential replacement cards: Fire Shrine Keeper is an evasive body that works well with the anthem of the uncommon chandra, and between uncommon chandra and steamkin, hitting 8 mana to bolt two creatures is possible, if not consistent. Scampering scorcher (the 4 mana, get three 1/1 elementals with haste) puts a lot of bodies onto the battlefield for uncommon chandra to pump. Adding green for Creeping Trailblazer also seems very good when you're flooding the board with tokens; it pumps them while being able to pump itself.

Icon of ancestry might be decent; pumps all your elementals while letting you dig for more cards later in the game; unlike trailblazer though it's not a creature and does little on the board by itself. I also wonder if Chandra Fire Artisan would be good here; she draws you cards (2 cards a turn with regulator) and 3 mana chandra can pump her up to that -7 ultimate very quickly and smacking an opponent for 7 is something I for one am glad to do.

Thanks a lot for the feedback, Fiender. I will definitely be making a lot of changes to my deck after reading your comment. I will exchange Chandra's Embercat with Fire Shrine Keeper , remove Lavakin Brawler to add more of the other cards, replace Mask of Immolation with Icon of Ancestry , and move Chandra, Awakened Inferno and Leyline of Combustion to the sideboard. I won't be adding in Creeping Trailblazer because I really want to keep it straight mono-red, though I was contemplating putting that in when I first made the deck. All-in-all, you have been a huge help and I thank you very much.