Strongly consider:
** Jeskai Ascendancy - Could be a wincon with Ramos out and enough charms
* Mirari's Wake - Turn 4-5 Wake can let me go off with Ramos on turn 5-6
Mask of Riddles
* Etherium-Horn Sorcerer - Will make infinite mana with Ramos and Corpsejack as long as I don't hit artifacts
* Shielding Plax - Protection that replaces itself!
* Transguild Courier
** Dragonlord Dromoka - Once we get going with Ramos, there's no stopping us
* Damia, Sage of Stone - Keep my hand stocked
* Forgotten Ancient - Monocolored, but can ramp a lot with Ramos
Find // Finality - Boardwipe with bonus counters, or get back Marchesa or Corpsejack
Flesh // Blood - Graveyard hate that grows Ramos, and/or dome someone for a lot
Debt to the Deathless - Mana sink and finisher that can guarantee the game ends when I go off
Kaya, Ghost Assassin - Card draw, or keep Ramos safe for a turn
Surrak Dragonclaw - Get a Ramos through counters or through blockers
Gates Ablaze
Gyre Engineer
Bounty of the Luxa - Ramp or card draw every other turn
Growth Spiral
Forge of Heroes

Need:
$$ Maelstrom Wanderer - GREAT if I can cast it for 5 with Ramos out, but also ok if I cast it before Ramos to give him haste
$$ Reyhan, Last of the Abzan - Get value if Ramos is spot removed
$$ Zacama, Primal Calamity - Crazy ramp with Ramos and Jodah or Fist, as well as a great mana sink. Consider pairing with Temur Sabertooth for infinite mana
$$$ Reflecting Pool

Consider:
Simic Guildmage - Create extra counters with Corpsejack/Snek
Biomantic Mastery
Drastic Revelation
Ancient Excavation - Upgrade a hand full of lands
Firemind's Research - Card draw or finisher on combo turns
Sleeper's Robe
Mayael's Aria
Chorus of the Conclave - Spend extra mana to start Ramos off with counters (or other creatures for Marchesa protection), but this costs 8, and Ramos is already so expensive that I probably won't have the extra mana to start him off (would have to cast him for 11 the first time)
Sire of Stagnation - Can draw lots of cards
Epic Experiment - If cast off of Ramos mana, could generate insane amounts of mana to put into a game winning mana sink
Krasis Incubation - Makes infinite mana with Ramos and Corpsejack or Constrictor
Expansion // Explosion - Mana sink, finisher and card draw, or just copy a good spell
Master Biomancer
Trap Essence - If I can counter a creature with this with Ramos out, I get all the 5 counters needed to get started
Emergency Powers - Refill hand and hopefully get something good out
Niv Mizzet, Parun
Discovery // Dispersal - Multicolored cantrip, or value removal
Bioshift - Get some existing counters to Ramos quickly
Abzan Ascendancy - 3 colors, and potentially protect a lot of dudes with Marchesa
Armament Corps - Three colors and get some counters
Quicksilver Dagger - Can draw a LOT with Jeskai Ascendancy
Fevered Visions
Scarscale Ritual
Thoughtflare
Senate Guildmage
Mathas, Fiend Seeker
Sphinx's Insight
Kynaios and Tiro of Meletis - Card draw, ramp, good blocker and FOUR colors
River Hoopoe
Jori En, Ruin Diver
Consult the Necrosages
Pilfered Plans
Disinformation Campaign
Bred for the Hunt
Nin, the Pain Artist
Mina and Denn, Wildborn - Ramp that can also force through a big Ramos
Cloudblazer
Dark Intimations
Niv Mizzet, Dracogenius
Tatyova, Benthic Druid
Nekusar, the Mindrazer
Mercurial Chemister
Dromoka the Eternal - Will this ever (except maybe the first time) help Ramos?
Bedevil - Strong, multicolored removal
Altered Ego - Multicolored clone that brings some counters to the battlefield
Marchesa's Smuggler - Hasty, unblockable Ramos
Sphinx of the Guildpact
Righteous Authority
Conjurer's Ban
Obzedat's Aid - Multicolored goodstuff. Can get back Door
Baleful Strix - Cheap, 2 colors, replaces itself and is a good blocker
Yidris, Maelstrom Wielder - Lots of colors, and potentially lots of cascading
Manamorphose
Sygg, River Cutthroat
Deathreap Ritual - Can keep my hand well-stocked in an action-filled game
Bound // Determined - Cheap cantrip for two colors that forces through the rest of my turn, or sac something to get back important cards
Anafenza, the Foremost - Cheap, multicolored creature that can put counters on Ramos
Restoration Gearsmith - Get back Door to Nothingness or a creature
Invoke the Firemind - Card draw or finisher
Isperia, Supreme Judge
Coerced Confession
Dimir Cutpurse
Soul Ransom
Oloro, Ageless Ascetic
The Ur-Dragon - Actually generates mana, as well as card advantage and a fatty
O-Kagachi
Melek, Izzet Paragon - Multicolored synergy with charms
Fusion Elemental
Common Bond - 4 counters for 3 mana at instant speed
Shambling Shell
Nivmagus Elemental - Can be ok with Bioshift
Ojutai's Command
Silumgar's Command
Silumgar, the Drifting Death - Board wipes
Harbinger of the Hunt - Manasinking boardwipe
Savage Ventmaw - Another dragon that generates mana
Ojutai, Soul of Winter - Tap down blockers?
Rakdos' Return
Skarrg Guildmage - Trample up
Teleportal - Get Ramos through, or even Ramos and friends
Atarka, World Render - Ramos hits even harder
Dragonlord Kolaghan - Hasty Ramos
Anax and Cymede - Get this dragon trampling
Ghor-Clan Rampager - "Uncounterable" combat trick that gets Ramos through blockers
Ride Down - Removal and get through a Ramos hit
Enduring Scalelord - Grows with Ramos
Scion of the Ur-Dragon - Consider this if we put in a lot of dragons
Taigam, Ojutai Master
Ashen Rider - Multicolored goodstuff to discount
Kaervek the Merciless - Multicolored goodstuff to discount
Deathbringer Liege - Gives me incidental value from a lot of my charms, and grows most of my creatures
Debtors' Knell - Multicolored goodstuff to discount
Teysa, Envoy of Ghosts - Multicolored goodstuff to discount
Sisters of Stone Death - Multicolored goodstuff to discount
Dragonlair Spider - Multicolored goodstuff to discount
Skullbriar, the Walking Grave - Cheap multicolored creature that synergizes with the +1/+1 cards
Teneb, the Harvester
Crosis, the Purger
Dovin Baan
Ashiok
Vanish into Memory
Prime Speaker Zegana - Do I have enough creatures for this?
Gleam of Battle - Probably not enough creatures for this to have any point

Consider (mono-colored):
Biogenic Upgrade - Worst case for this with Ramos out is 8 counters
Scapeshift - Get the rest of the gates
All Suns' Dawn - Monocolored, but does say "each color"
Vivid Revival - Worse than All Suns' Dawn
District Guide - Get a gate
Pyroconvergence - Removal and wincon in one
Lobber Crew - Wincon
Cultivate
Farseek
Kodama's Reach
Cyclonic Rift
Sunbird's Invocation
Swarm Intelligence
Hardened Scales
Inexorable Tide
Crux of Fate

Consider (colorless):
Etched Monstrosity
Lightning Greaves
Swiftfoot Boots
Rampaging Monument - Wincon
Commander's Sphere
Primal Amulet
Dragon's Hoard
Darksteel Ingot
Signets
Ugin, the Spirit Dragon
Prismatic Geoscope - Depends on manabase. Probably not

Consider (don't have):
Glint-Eye Nephilim
$ Hadana's Climb
Gloryscale Viashino - Can kill fast
$$$ Maelstrom Nexus
$$$ Maelstrom Angel - Would be amazing, but not worth the money
$$$ Ajani, Mentor of Heroes - 5 counters for Ramos
$ Teferi, Timebender - Untap Door to Nothingness or draw cards
Ezuri, Claw of Progress - Could be really good if I play more small dudes
Ghave, Guru of Spores - Move around counters
Kraum, Ludevic's Opus
Hindering Light
Cerebral Vortex
Arjun, the Shifting Flame
Azra Oddsmaker
Beck // Call
Crackling Drake
Borborygmos
Zegana, Utopian Speaker
Ishai - Multicolored grower to Bioshift from
Marath - Good value if I have a counter doubler
Oath of Ajani - A cheaper Abzan Ascendancy
Olivia, Mobilized for War - Get Ramos a counter on him when entering
Shapers of Nature - A more expensive Zameck Guildmage
Apocalypse Hydra - Cool if we go a Bioshift route
Birds of Paradise - Monocolored, but says "any color"
Witch-Maw Nephilim - Spells payoff and many colors
$$ Bringer of the Blue Dawn
$$$$ Karrthus, Tyrant of Jund - Just pure power, and hasty Ramos
Sarkhan Unbroken
Pure // Simple - Useful, multicolored and versatile
Twisted Justice
Primeval's Glorious Rebirth - If I have enough permanents
Xira Arien
Khenra Charioteer - Give Ramos trample
Colossal Might - Combat trick to kill someone with Ramos
$ Ajani, Valiant Protector - Grow Ramos (make mana) or search for a wincon
$ Vraska, Regal Gorgon - Grow Ramos and/or get him through a blocker, or just removal
$$ Vraska, Relic Seeker - Removal or create some dudes
$ Arlinn Kord - Help Ramos attack
Engineered Might - Trample over with a huge Ramos
Nature's Blessing - More flexibility, including trample
Surge of Strength - +6/+0 and trample, but at the cost of two cards total
Increasing Savagery - Monocolored, but it's a +6 mana with Ramos
Incubation Druid

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Considered cuts:
Guild Summit - Having to tap the gates makes this a pretty expensive card draw spell if I don't get it early
* Some borderposts (Veinfire probably goes first)
Genju of the Realm - Five colors is nice, but 2 mana to activate the land might be a bit much. Could probably safely be replaced with Transguild Courier
** Cruel Ultimatum - The triple black might be tough, and I might not have enough dudes atm for the reanimation to be worth it
* Crystalline Crawler - Colorless, but synergistic. Probably too slow
** Nicol Bolas, Planeswalker
Circuitous Route - Monocolored
Mystic Monastery / Crumbling Necropolis / Savage Lands / Jungle Shrine / Sandsteppe Citadel
Bojuka Bog - More needed elsewhere probably

Azorius Charm - All the modes are nice, but none of them are great. I do need a way to gain life, though.
* Izzet Charm - All the modes are quite mediocre
Dromar's Charm - The counter mode is the only worthwhile mode
** Grixis Charm - Bouncing a *permanent* is nice, and -4/-4 is enough to be able to kill something significant, but it still feels somewhat underwhelming
Bant Charm - Only countering instants is a bit restrictive, but all the modes are decent, and cover enough bases that it's probably worth it
Esper Charm - Only two cards might not be good enough, but actually going up cards, with a backup of removal is probably worth it
Sultai Charm - Decent removal spread, with the option of replacing itself in the worst case

--------------------------

Cuts:
Darigaaz's Charm - None of the modes are really that great, even though some (Raise Dead) are nice
Gruul Charm - Good against fliers (and thieves), but not really worth a slot
Orzhov Charm - The destroy mode is the only useable one, which makes this just bad
Counterflux - The soft counters from the charms are probably enough
Putrefy - With the charms, I probably have enough ways to destroy both creatures and artifacts
Utter End - Good card, but costs 4 and only gives 2 colors
Gatecreeper Vine - Probably not good enough to justify being monocolored. Consider adding back in if I really need early blockers
Narset Transcendant - I can't protect her, I don't actually want to ult her, and unless I'm rebounding something like a Cruel Ultimatum, she's not really worth it
Rith's Charm - Land destruction is nice, but the other modes are underwhelming
Mardu Charm - None of these modes are particularly good in EDH
Dimir Charm - The counter mode is the only good one, and it's mostly just good for countering sweepers
Temur Charm - Mana Leak can be good, but usually won't be enough. Fight will probably only work with Ramos, and puts him at risk. Nice to stop chump blockers
Garruk, Apex Predator - Probably not enough immediate impact to be worth the mana, but it's nice as a thing to cheat out with Jodah/Fist
Selesnya Charm - Only kills very big things, but the option of letting Ramos trample over chumpers is nice too
Opal Palace - The colorless is next to useless, and I'm not likely to cast Ramos a lot of times during a game
Nomad Outpost - The three least used colors
Arcane Sanctum - Tapped with two of the less used colors
Simic Charm - Protect Ramos from spot removal, or other mediocre modes. Assure is probably a good replacement
Jeskai Charm - The lifelink option is nice to have, and Griptide is ok, but the total package is not amazing.
Treva's Charm - All the modes are quite restrictive
Fist of Suns - I only have ~10 cards in the deck that benefit from the alternate cost, and this being colorless doesn't trigger Ramos and can't be tutored for
Zhur-Taa Druid - Quite fragile, and will probably draw hate. Replaced with the fifth Borderpost
Sylvan Reclamation - Expensive and only two colors, but the fixing option is nice
Combine Guildmage - Too slow
Terramorphic Expanse - Slow, I don't have a lot of basics, and it's more needed elsewhere
Nicol Bolas, God-Pharaoh - Move to Bolas deck