Fetch lands, shock lands and pain would run the deck faster. Also, 20 lands is slightly too little. What is cool about the shock lands is the fact you can pull them out with the fetch lands. Broken combo.

[Deflecting Palm] and [Triton Tactics] are cards not as effective. Yes TTact can target 2 creatures, but it is not a card that is aggressivly reliable. There are a ton of amazing enchantments that can give you the upper hand like [Gift of Orzhov] or [Aqueous Form].

Instant spells like [Temur Battle Rage] should also be considered.

[Spellheart Chimera], [Nivix Cyclops], and [Mantis Rider] are heavy in this deck because disrupt the flow of your deck. In all honesty [Favored Hoplite] can beat and in most cases should down your opponent by himself. Only sure way an opponent can deal with him is exile.

Also you need cards cards in your hand at all times. So simple cards like [Defiant Strike] or [Stratus Walk] are great. You use them and they replace a itself by letting you draw a card.

Playing deck like these where you constantly play cards without refilling your hand gets rough fast after turn 3-4+.

Ok thanks for listening.

I would replace you're 3 Nivix Cyclops and 2 Guttersnipes with 3 Jeskai Ascendency's and 2 Monastery Swiftspear's. With all the instants and sorcery's your playing, it would make a lot of sense to improve all of your creatures by targeting them and also gaining the +1/+1. Get rid of Evolving Wilds and add 2 Shivan Reef and 2 Battlefield Forge's to increase speed. The last thing you want to do is give someone else a turn advantage by having tapped mana when it can be prvented, and it also improves you're overall color base. Flooded Strand's would be nice, but may be too expensive.

I would remove Defiant Strike for 2 Serum Visions and 2 Distortion Strike I know they may be harder to get your hands on, but They would definitely increase the decks overall strength Visions for the Draw and Distortion for its fantastic synergy with Prowess/Heroic Creatures

im surprised you didn't use the best cards for heroic. Dynacharge and Weapon Surge are the best because the target everything and you get a million heroic triggers

plus DTK is out so try some rebound cards like Artful Maneuver

Overloading doesn't target all creatures since it says replace target with each meaning it can only trigger heroic if not overloaded

drop Lightning Bolt and Guttersnipe and just make it standard.

I would drop Lightning Bolt and Guttersnipe, but then in a few months Theros won't be standard anymore and there goes half my deck. I don't play in nearly enough tournaments to justify having this deck be standard anyhow. I mostly just play with friends, but I do enjoy keeping at least one standard deck.

you know, this can be a standard deck if you take out Guttersnipe and Lightning Bolt for Lightning Strike and it can be a good standard deck.

Run Gods Willing as a 4 of, one of the best cards ever because if someone tries to kill you creature and you can say NOPE or you can swing for game and say you can't block me.