Academy Rector - On-board tutor, defensive deterrent, brings any enchantment onto the battlefield and potentially does it at instant speed with sac outlets like Goblin Bombardment and High Market. Typically used to find missing combo and engine pieces. One of the most powerful cards in the deck.
Recruiter of the Guard - Finds lots of critical pieces for the deck. Effectively a combo piece tutor by finding Seasoned Pyromancer, Academy Rector, or Grand Abolisher for protection from interaction on the turn you go off. It can also find mana fixing and ramp via Weathered Wayfarer and Boreas Charger. This card does some serious heavy lifting.
Gamble, Idyllic Tutor, Enlightened Tutor - More tutors! There's definitely a critical mass of these, and one of the reasons the deck has more consistency than one would expect for Boros. Gamble occasionally wiffs, but the risk gets mitigated by having a hand stuffed with lands and other cards as well as multiple ways to recur lost cards.
Land Tax - One of the key enablers of the deck. Card advantage largely comes out of rummaging away lands in hand into other cards, plus wheel effects. It is one of the few cards that actually puts additional cards into hand and nets card advantage, and it can also provide fuel for some of the board control elements like Molten Vortex and Seismic Assault. Also since it's an enchantment there's several ways to tutor for it.
Scroll Rack - the O.G. partner to Land Tax. It's an all-star on its own right, turning lands and dead cards into potentially more useful cards. With the various shuffle effects, the card advantage potential of Scroll Rack gets that much better.
Tectonic Reformation - Scroll Rack #2. Forms one of the core engines of the deck with Land Tax, and it's a great engine on its own right when looting away lands. With Surly Badgersaur, all lands cycle for free which is just gravy.
Outpost Siege - One of the finishers of the deck when paired with the Opalescence + Parallax Wave loop. Also just fantastic for the Khans mode card advantage and is sometimes a tutor target for when there's nothing else I can assemble on the board.
Pursuit of Knowledge - One of those sleepers that few decks seem to run. It's a pet card, but it also fits so perfectly when there's so much looting going on. Normally in a white-based deck a card like this would be too painful to run, but when paired with cycling lands and other loot effects it becomes way easier to activate within a single turn cycle. Personally I love it for the surprised expression on my opponents' faces when they see it. It can also do fun things with repeatable recursion from Starfield of Nyx.
Magus of the Wheel, Wheel of Fortune, Runehorn Hellkite, Reforge the Soul - Wheel effects. Refill the hand, make massive amounts of mana with Smothering Tithe, combo off with the latter + the non-creature versions + Underworld Breach. Magus comes down early but rarely eats removal, and Hellkite is fairly easy to sneak into the graveyard with multiple discard outlets in the deck.
Mesa Enchantress - The deck runs lots of enchantments, so it fits really well.
Skullclamp - Most of the creatures in this deck are pretty sacrificial thanks to their ETB abilities. Since many of the bodies are pretty disposable, Skullclamp becomes a solid option for generating even more value for cheap. Most fun when paired with Spirit Cairn and other repeatable token generation effects.
Bag of Holding - When it comes to a deck that does a ton of discarding, finding ways to refill your hand becomes pretty critical. This artifact does that in spades, holding onto your loot while turning dead cards into new ones on its own. The bag does some fun tricks with Sun Titan, Seismic Assault, Tectonic Reformation, and C20 newcomer Surly Badgersaur. Also acts as an insurance policy for wheel effects and discard effects from my opponents.
Desert of the True, Desert of the Fervent, Forgotten Cave, Secluded Steppe - Cycling lands. They are tutorable with Weathered Wayfarer, serve as fuel for Pursuit of Knowledge, and in the case of the deserts, provide additional utility with Scavenger Grounds for graveyard removal. Sunbaked Canyon gets an honorable mention as effectively a land that cycles from the battlefield.
Geier Reach Sanitarium - Tutorable, repeatable rummage land. Interacts really well with Smothering Tithe and Spirit Cairn.
Cavalier of Flame - This card has a metric ton of utility packed into it. ETB selective rummage, mass haste and team buff, aggressive stats, significantly contributes to your devotion count, and a death trigger that has incredible synergy with this deck as lots of lands get dumped into the graveyard.
Seasoned Pyromancer - Great rummage trigger, and it turns useless nonland cards into tokens while digging me into combo pieces. It's a fantastic early game card, generates bodies for Skullclamp, and it can serve as a tutorable combo piece. If I'm hellbent it's also pure card advantage. With a Gift of Immortality and sac outlet it becomes a card advantage engine.
Faithless Looting - Digs real deep for cheap, turning lands in hand into potentially real cards. Also sets up explosive plays with mass recursion like Replenish, and it triggers discard payoffs. All around solid card.
Restoration Specialist - Decent 2-for-1 recursion on a tutorable body. It gets the nod over Auramancer variants that have an ETB trigger because I can activate it at instant speed and it gets artifacts, a few of which are valuable.
Sun Titan - Format all-star, combo piece, great beater. Holy crap does it do work here. Most of my cards are CMC 3 and below, so the Titan usually has targets. Great beater, but mostly it's the triggers we care about. It combos with Gift of Immortality and Goblin Bombardment, both of which are easy to excavate out of the yard. Also does insane things with one of the other enchantment combos in the deck, which I'll elaborate on later.