You all made it happen, here's the breakdown for all the cards I run:
Altar of Dementia-free sac outlets are insanely good, and although this Altar doesn't do anything off sacking an egg (although try attacking with a Pathbreaker Ibex and then sacking 'em, that's fun!), it's still free to activate and costs very cheap to cast. Also, alternative wincons are important in combat-damage-based strategies--ya never know when someone will pull up in their Mile-High Wall deck.
Angel of Destiny-very interesting addition to the Pathbreaker/Kamahl+Moraug/Razer wincon, AoD is just a weird card in general. But it pulls its weight, and isn't as scary as the other wincons in the deck--ergo it doesn't draw as much hate and removal.
Apex Altisaur-indubitably the best boardwipe creature for this deck. The Altisaur is different from other creatures of the like because
A. it's an optional trigger, unlike Sunblast Angel
B. it's one-sided, unlike Novablast Wurm
C. you don't have to cast it, unlike Myojin of Cleansing Fire or Wakening Sun's Avatar. Because of all that, the Altisaur is a pretty busted card (don't even get me started on it with Avacyn, Angel of Hope, Pebbly Horse-Guy, or Pathbreaker Ibex).
Arcane Signet-prooooobably shouldn't exist as a card, but we don't mind! Two mana ramp is what we want, and the ELD addition to the Ravnican signets is very top-tier.
Archetype of Endurance-Interesting card from an interesting cycle. This card's second ability doesn't matter most of the time, but when it does it's huge. The first is almost always useful, as for some reason people seem to want to remove our stuff ;)
Ashnod's Altar-in a deck with a bunch of creatures sporting 6+ generic mana pips, and with a commander who has a activated ability, this altar is a beast.
Avacyn, Angel of Hope-every deck needs protection (safe is sexy!), and Avacyn is the undisputed best source of constant board-wide indestructibility there is.
Bala Ged Recovery
-Recursion is a useful tool in any deck, but it often sits in your hand for a while without a use if none of your important pieces are hitting the grave. But with Recovery, you can always just hit a land drop if needed, and in those scenarios where you need your Path to Exile back to kill an Ulamog, the Ceaseless Hunger, well--you can do that too.
Bloodstained Mire-way back when I started playing magic, I bought a Khans of Tarkir fat pack (what are they called now? Bundles?) and cracked Mire and a Polluted Delta. When I first put Atla together around a year ago, I was annoyed to find that both my fetches were off-color--and that I couldn't play one of them at all. But since then, I've come to realize just how good fetches are, and that you should probably run all you can with suitable targets such as shocks, tangos, etc. (remember you can proxy...)
Boros Signet-simultaneously the worst and best signet in the deck. BSignet gives a better chance at letting us play Atla T3 off it because of how many green lands there are in the deck--but there are a lot of green sources for a reason: we play a lot of green cards. And so it does a little less work late-game, but still definitely not a negligible amount.
Bountiful Promenade-honestly probably worse than the shock lands, the Battle Bond land cycle is still quite good. I doubt they're good enough to warrant putting all three into the deck, but the colorfixing is very very solid and it's a good card to have (especially when your friend will trade their Expedition version (≥w≤))
Brainstone-this Brainstorm knock-off is actually very good at everything we need it to do: it helps hit land drops, it helps stack our library with beaters that are stuck in hand, and it comes down early so we can make the most of our mana. I've surprisingly found it to be better than Scroll Rack in playtesting, simply because of how it draws you the cards first, rather than you needing to tuck cards to draw more.
Brutalizer Exarch-what a card this is! From tutoring a Pathbreaker Ibex so we can go sicko mode to tucking that pesky Rhystic Study to ne'er-come-back, The Exarch is an all-star in so many ways. See the tutor section for how to use it.
Canopy Vista-the Tango Lands are basically OG duals in a deck like this with 20 basics, and we know how important good colorfixing is.
Cavalier of Dawn-removal creatures are splendid because they can basically act as Force of Vigors--that is, be free. CoDawn can also grab an Painful Chair or Summoner's Egg (everyone loves more free creatures!) that's ended up in the GY.
Cavalier of Flame-it's important to have a creature to just straight-up draw cards off of (in opposition to cards like Garruk's Packleader, who need other pieces to work)--sometimes you really need to hit a land drop, and a one-man digger like CoFlame is important. Nevermind his other abilities... haste is always nice, especially when it firebreathes our whole team, and pinging our opponents on LTB is an inconspicuous advantage.
Cinder Glade-a pretty reliable fetch target, glade is good enough to be prioritized over the shocks sometimes. Just good ol' quality colorfixing.
Combustible Gearhulk-card draw on creatures is surprisingly important, even in a deck with access to things like Jeska's Will and Garruk's Uprising. The reason why? We can't crack into those cards, and sometimes sacking an egg is our only option for value-generation. But without creatures like the Gearhulk, that value generation can't be in the form of cards drawn, which makes it harder to hit land drops, etc.
Command Tower-all the colors. What more can you want? (Well, to be fetchable, but that would be busted)
Congregation at Dawn-I already have a very long tutorial about Congregation in the Tutor section of this primer, but suffice it to say, putting Pathbreaker Ibex, Port Razer, and Samut, Voice of Dissent into play all at once ends games very quickly.
Cream of the Crop-bad names aside, CotC basically reads "whenever a creature enters the battlefield under your control, scry 4". And being able to smooth our draws so efficiently is a hard thing not to want in any deck.
Deflecting Swat-yay, free spells! Swat comes in handy in all sorts of situations, be it a Commander's Insight, Time Stretch, Swords to Plowshares, Counterspell, or even an enemy Deflecting Swat!
Elemental Bond-card draw is excellent when it comes down early and gives recurring value, and being able to draw off the ETB of every creature in the deck (besides Atla, Angel of Destiny and Seedborn) has power untold.
Fabled Passage-more fetchlands, except more affordable! And they don't ping you! What's not to love? Passage works well in a deck with 20 basics, and although it can't get shocks and things it can get W, R, or G.
Faithless Looting-cheap, semi-repeatable draw is very nice in any EDH deck; since it can be a little hard to draw into lands without our engine already running, Faithless is very welcome in any hand. We are ok to pitch cards, since a lot of beaters get stranded in hand with no hope of being hardcast anyway.
Farseek-nothing trumps the feeling of grabbing your pick of the shock-land-litter on T2. Basically guarantees having the right colors for the essential turn-3 Atla.
Flawless Maneuver-sometimes, our opponents get a bit tricky. They wait for us to tap out, then have the gall to cast a boardwipe! Well, we won't stand for that. This card is one of the ultimate "gotcha!"s out there, and it's worth using just to save Atla on an otherwise empty boardstate.
Flooded Strand-another day, another fetch. I know I sound like a broken record here, but getting our colors down is very important. Strand has an ZNR Art Card, so we can cheese the cost a bit (but don't tell anyone).
Force of Vigor-the premier Arti-Chantment removal spell. We have so many creatures in this deck that we will have no chance of hardcasting (e.g. Kamahl, Heart of Krosa, Apex Altisaur, Archetype of Endurance) that pitching them to FoV is not a problem.
Garruk's Packleader-much of this deck's ability to spin its wheels for hours comes from cards such as this one. Crack an egg, draw a card. Play a creature, draw a card. Play a land, make an egg, crack it, draw a card. You can see how this leads to immense value.
Goblin Bombardment-very annoying to play against, very fun to play with. We can mow down token armies with this one, and going to the face with chip damage is never wrong nor insignificant.
Greater Gargadon-you haven't lived till you see your opponent realize they can't interact with your sac outlet at all. Free sac outlets are very powerful, and 1 cmc ones are only better. Doesn't hurt that it turns into a beater in the late-game either.
Harmonize-it's important to have card draw that isn't creature-based, in case we're short a land in the early game and can't possibly draw enough off a Elemental Bond to ensure getting one. I don't love having to play this card (feels like a color-pie break), but it softens the sadness that there's such a cool Japanese version from STA.
Heroic Intervention-I can't tell you how many times this card has single-handedly changed a would-be loss to a win. People just don't expect such a catch-all (stfu Cyc Rift, we all hate you, die) answer.
High Market-sac outlets are great, and free ones are better... but having one on a land is a sort of excellence unparalleled in RGW. Colorless lands are dangerous, but as long as we keep the bare minimum we can run such great utility as the market.
Irregular Cohort-this card had been on my radar for some time before I added it, but somehow in my head it never seemed as strong as I now know it to be. What Cohort allows for is one egg crack to turn into two, and THAT is sometimes enough to catalyze one of the hour-long turns this deck is all about. It works especially well with Terror of the Peaks, Kodama of the East Tree, and Ashnod's Altar//Thermopod.
Into the North-2 mana ramp--what more could you want? This is functionally a second Rampant Growth, but that's saying something. Nothing makes me want to keep a hand more than seeing something like Into the North in it.
Jeska's Will-one of the best mono-red cards in the format. Jeska's Will provides so much generically powerful value that it really doesn't matter that it has no outstanding synergy with the rest of the deck--it just does its thing and increases our win-chance by a metric ton.
-the ZNR MDFC's are truly incredible. This is one piece of interaction will never get stuck in hand when the board is safe, because it can always just be played as a land!
Kamahl, Heart of Krosa-another redundant piece in the Moraug-Ibex synergy, Kamahl can also animate lands to act as sacrifice fodder, trigger Kodama of the East Tree so as to put basically anything from our hands into play, and give insane desperation value with Skullclamp.
-another interaction MDFC, except this time it cares about quality over quantity. But that's ok! We have plenty of both in this deck, and creatures like Avacyn, Angel of Hope and Apex Altisaur don't mind a bit of fighting at all.
Kodama of the East Tree-from cheating out baddies like Avacyn, Angel of Hope to going semi-infinite with Nesting Dragon, Kodama is one of the creatures I most often hope to hit off an egg crack. Having a massive hand after a big turn with a Garruk's Packleader often means nothing without Kodama, as the average CMC of the deck is prohibitive of just casting everything. But with Kodama, that huge hand dwindles as we throw it all down on the table following just a few smart plays. Powerhouse.
Moraug, Fury of Akoum-extra combat phases are best in sets of 12, isn't that what they say? Although Moraug can give us even more if we play our cards right! Being able to untap Atla every time is an important thing to notice, too.
Mutavault-up there as one of the best manlands, vault serves triple purpose in this deck:
As a land, to well... have lands
As an early attacker, since we don't run any low-cmc creatures to do the job
To trigger Atla if we sac/block with it. And given that those are all important jobs, I think mutavault's spot is safe.
Nature's Chosen-don't underestimate the second half of this card! Untapping a Sol Ring can get us the gas we need to finish a combo line, and untapping a Snow-Covered Mountain to let us hardcast Cavalier of Flame is amazing. But it also just lets Atla make another egg, and that by itself is wonderful.
Nature's Lore-see entry for Three Visits. They are functionally the same card, and given EDH is a singleton format, we'll take redundancy where we can get it.
Nesting Dragon-probably the most efficient way to get more eggs into play. Nesting Dragon goes nuts with land-based ramp spells or a good sac outlet. Also makes flyers, which is a nice, clean way to get over annoyingly large token swarms.
Protean Hulk-this egg-bearing behemoth can grab most anything we could ever want for a situation, from a Shalai, Voice of Plenty to protect our boardstate, to a Pathbreaker Ibex to end the game, to a Cavalier of Dawn to rid ourselves of a nasty threat. Truly an MVP.
Pathbreaker Ibex-the first entry in the now ever-important ibex-and-friends+Moraug/Razer synergy, the ibex is almost certainly the best of that bunch on its own. All ya need is a large enough creature and couple others and you'll be swinging hard very fast.
Port Razer-essentially a second Moraug. Ibex/Kamahl/Angel combo aside, Razer is just a solid way to make decent attacks into bigger ones.
Prismatic Vista-Colorfixing: can't live without it. This is a very efficient way to grab the color we need, and the fact that there's an Art Card allowing me to not have to spend a billion dollars on it is just icing on the cake.
Rampant Growth-I want to say this card is literally where the term "ramp" came from, but that's probably not true. Whatever the case, fetching a basic on 2 is never bad.
Rhythm of the Wild-the best instance of the Riot mechanic. The bad thing with haste enablers--sorry, the bad things with haste enablers is that they
don't do much post-combat unless the creature given haste has a tap ability (only Samut does in this deck, and she already has haste!)
don't do anything when stacked. Double haste isn't a thing, unlike double flying ofc.
But Rhythm gets past both of those--it can put counters on things when haste just isn't what's needed. And making stuff uncountable will very quickly make the blue player at the table very uncomfortable.
Sacred Foundry-definitely the Shock I tutor for the least, it is still a shock nonetheless--it can help power a Cavalier of Flame, and guarantee I can get the right colors with Bloodstained Mire. Good card.
Samut, Voice of Dissent-doublestrike is a beast with Ibex effects--and flash is a boon with a Seedborn in play. Haste to everything is a necessary evil on a pop-off turn, and untapping Atla is powerful when gas is needed.
Seedborn Muse-The creature I tutor for the most in this deck, SBM is a one-spirit army--although the way in which it's good means it brings along some friends. Usually, with Seedborn out, we get back to our turn with 5ish more creatures on-board than we started with. And that wins games! If you're ever unsure what to tutor for, Seedborn is the answer.
Selesnya Signet-I've said it before and I'll say it again: 2 mana ramp is a force to be reckoned with. The Ravnican signets are so good too because they allow you to have all our colors SO MUCH easier(ly??)
Shalai, Voice of Plenty-a nice persistent protection effect. Shalai stops direct targeting all over the place, even to the face! She works well in conjunction with Archetype of Endurance (Shalai's only weakness is that she doesn't give herself hexproof) and Seedborn Muse.
Skullclamp-sac, draw, repeat. The practical only downside is the magic all has to happen at sorcery speed. But when you're drawing a bucketload of cards, who cares?
Sol Ring-turn 2>= ramp is super important in this deck, as Atla really needs to hit the table T3. Having a lot of extra colorless mana laying around is nice when all your spells are so beefy as well.
Soul of the Harvest-card draaaaaw! This one has a bit of a relevant body though, and a useful keyword. Can do some attacking as well as drawing.
Stomping Ground-Dual lands are good, surprise surprise. Ground is by far the land I tutor for the most, as white is, shall we say, an afterthought past Gruul in this deck and Magic as a whole.
Stonehoof Chieftain-ol' rocky equine-bloke himself. Granting two very relevant combat keywords at once, as well as holding a sizable body himself... all-star.
Summoner's Egg-works well with Cavalier of Dawn for an extra go at the spin, and can get an 8-drop stranded in hand into play in the blink of an eye.
Swords to Plowshares-proooobably the best removal spell in the format. It's very hard to have a white deck that doesn't want Swords.
Talisman of Conviction-just like a signet, except not at all! This is a very interesting piece of our 2-drop ramp package, in that it can tap for two colors of mana separately. Obviously Arcane Signet can do the same, but outside of that our rocks are tied up in forever-two-color land. And remember: life is a resource, taking a pain once, twice, three times, four times, etc. is ok to fix our colors!
Temple Garden-useful in tandem with Flooded Strand, as allows for it to get green mana. And we use a lot of green mana in this deck!
Terror of the Peaks-this draconic Warstorm Surge-on-a-stick is perfect for closing out games against those annoying Propaganda players (you know the ones), or just removing threats across from us at the table. Also can be used to burn up eggs in a pinch if we're missing a sac outlet.
The Great Henge-card draw? Check. Ramp? Check. Life gain? Why not? This card does everything, and it only costs about 4 mana on average.
Thermopod-just a little Phyrexian Altar on a slug. Very easy to perpetuate winning turns with a thermopod out. Also works well with Sneak Attack.
Three Visits-two cmc ramp is key, padawans. Forests are the dominant land type in this deck, so it's really no issue to have to get one with Visits.
Tragic Arrogance-We can save our commander in the early game with this, and a beater in the late. Never a bad card; everyone has a token or two laying around waiting to be chosen to stand alone. Gets around indestructible as well, which I think is of underrated importance.
Utopia Sprawl-after being rightfully yelled at for neglecting enchantment-based ramp in one of my many rants about sub-3 CMC ramp, I added a Sprawl to Atla and have never looked back. This card even allows for a sequence like T1-Sprawl, T2 Rhythm of the Wild, T3 Atla--and that's a force to be reckoned with.
-one of if not the best MDFC, imo--wheeling the huge uncastable cards out of our hand for a fresh grip is incredible. Not to mention it helps us hit land drops on the flip side!
Wayfarer's Bauble-easy castability (lets us keep a hand w/o green sources), ramps us when we need it, triggers Kodama of the East Tree, lets us say the word "bauble"... what a great card.
Winds of Abandon-when you play a creature-based deck, one-sided boardwipes are like a dream come true. Winds is not only that, but also a slightly worse Path to Exile if necessary as well. And in today's EDH climate, your opponents might not even be able to fetch enough basics to fulfill all the creatures they lost.
Windswept Heath-this should come as no surprise: fetchlands are good. Like, really powerful. Heath happens to be the cheapest fetch on the market rn, and it's in my colors no less--I just had to pick one up.
Worldly Tutor-cheap to cast, fast to work, reliable to function as needed... it's not hard to forget that Worldly Tutor is an instant, as are the abilities of most sac outlets in the deck... you can leave up a single green and nab an Apex Altisaur to clean up the board after combat before damage wears off. Super good.