Heroic strive to victory
The idea
Hopefully competitive Boros Aggro post-rotation Standard deck.
Fast cheap efficient creatures and spells with many cross-synergies (Strive, Heroic) designed to pump creatures and pop tokens to kill asap the opponent.
Consistent turn 5 goldfish, usually with a vast amount of damage in turn 5.
Initial build
The idea is to have as many synergies as possible. The key is that you can trigger Heroic and Prowess as many times as you can with your mana available, so many times you will be popping a token out of Akroan Crusader and a counter for all your creatures out of Phalanx Leader more than once in a turn, as well as triggering Monastery Swiftspear's Prowess ability, which will make her oftentimes a 3/4 just by sitting there while other creatures are being targeted.
Those 3 creatures are essential. Phalanx leader will be giving counters to the tokens also, making them suddenly more dangerous, as you might be swinging next turn for 6 or 8 instead of 3 or 4.
Spells targeting more than one creature are essential too as you can 2-for-1 trigger Heroics: Coordinated Assault and Launch the Fleet.
Dragon Mantle is essential card drawing and ability-triggering, the mana dumping is nice but playtesting 20 lands I have never been flooded... Titan's Strength is also essential, boosting your creature (also the toughness!), giving scry, and triggering both Heroic and Prowess.
Stoke the Flames looks versatile in this deck despite its cost as tokens can help casting it...
Theoretical Playtesting
I would not run however both full playsets of Dragon Mantle and Titan's Strength, as the deck risks not having enough creatures... 16 creatures are definitely not enough, so either we split 2+2 dragon mantle and titan strength, or we remove one of the playsets.
Enter a new creature. Soldier of the Pantheon seems a no-brainer, but lacking Heroic, I'm not sure of leaving it MB although it has to be among the 75 cards. Firedrinker Satyr is another option despite lacking Heroic, as both of them are 2/1 1-drops...
Researching for "Heroic", "Strive", "human (and soldier) you control" for RW in Gatherer, I am including Favored Hoplite (better than Satyr Hoplite) and considering Vanguard of Brimaz, another token generator.
Anax and Cymede seem essential because of trample though they also boost all creatures, but they are difficult to cast, and I am not sure some of their slots would not better suited with Spear of Heliod. Hall of Triumph is no good here as we have an unpredictable mix of white and red tokens, plus the Spear prevents opponent's creatures from attacking as it can remove them.
Iroas, God of Victory seems also promising but would screw the mana curve capped at 20 lands...
I am reluctant to include RW scrylands or lifelands due to the lack of speed... And without Sacred Foundry, I'm not sure of including fetchlands (and we also lack Arid Mesa)...
Initial goldfish playtesting and findings:
So, for now, these are the changes to the initial theoretical build:
Constructive criticism is appreciated!