Need:
$$ Resourceful Defense - If someone kills one walker, another might be ult ready. Might even let me ult all of them in a turn
$ Commodore Guff
$ Chandra, Legacy of Fire

Consider (have):
* Flux Channeler - Proliferate on basically every spell, but it is a creature and can disappear on a Narset trigger
* Mila, Crafty Companion - Makes attacking my walkers dangerous if you can't kill them all
Teferi, Master of Time - Strong staple that can give me extra turns, but also used in high-power. Super good with Oath of Teferi
Teferi's Talent - Super-power my walkers for the small price of 12 loyalty
Approach of the Second Sun - Can actually close out a game pretty quickly
Elspeth's Talent - Protect my walkers
Rowan's Talent - Copy a strong ability
Commander's Sphere - Colored rock that can cycle if flipped late by Narset
Ignite the Beacon - Tutor for a few walkers
Generous Gift
Cyclonic Rift - Narset can't overload it, but this is great for saving a bunch of walkers
Vanquish the Horde - Cheap sweeper
Kykar, Wind's Fury
Footfall Crater - Grant haste to Narset
Arcane Signet - More 2-mana ramp
Helm of the Host - More Narsets!
Cryptic Command - Counterspell that still does something when flipped by Narset, but UUU is hard if I need to cast it from hand
Sublime Epiphany - A counterspell that can also do other things when flipped by Narset, but I don't really have a lot of creatures to copy, and 6 mana is a lot to hold for a counterspell
Ajani Vengeant - Keep something tapped down, kill something small, or if I can ult I can basically get one person out of the game, although that seems a bit mean
Kasmina, Enigmatic Mentor - Card selection and chump blockers, plus making my walkers harder to target, but targeted removal is probably not going to be their biggest threat
Aqueous Form - Unblockable Narset with a scry
Aetherspouts - Stop a big attack from killing my walkers
Dockside Extortionist - Cheap ramp, but can't be cast by Narset
Djeru - Tutor for a walker I need, and otherwise make my walkers harder to kill
Smothering Tithe - Just great value
Ghostly Prison, Propaganda - Doesn't stop people from attacking my walkers, but it does protect me in case someone wants to just go straight for me instead of dealing with walkers, and they make Sphere of Safety better
Chaos Warp - Flexible removal that can be used on a dying walker to change it into something else
Dig Through Time - Card selection
Austere Command - Flexible sweeper
Jace Beleren - Just generic card draw, but the plus can earn me some goodwill. No ult to chase after
Gideon of the Trials - The emblem is sweet if I play multiple Gids
Contagion Engine - Proliferation
Brainstone - Another brainstorm effect that Narset can cast
Sphere of Safety - Might not be worth it with a low enchantment count
Gideon Jura - Can protect my other walkers by forcing creatures to attack old Gids, but can only affect one opponent
Throne of Geth - Sacrifice clues from Search the Premises to proliferate
Grateful Apparition, Thrummingbird - Proliferate on hit, but they die to literally anything
Martyr for the Cause - Chump blocker that proliferated the team, but probably not worth it when I can't control when he dies
Reconstruct History - I don't have a ton of instants, enchantments or even sorceries, so this isn't guaranteed to get full value. Even then, the cards in hand might not be worth this slot
Search the Premises - Get clues for each creature attacking me or my stuff
Mind Stone - Cheap mana rock with minor upside, but colorless only
Commander Sphere - Fixing and ramp, but Might not need 3-mana rocks with the amount of 2-mana rocks I have available
Jhoira, Weatherlight Captain - Draw a card off every walker and rock
Supreme Verdict, Day of Judgment - Another cheap wrath
Return to Dust - If any commander wants to play this in the modern times, it's Narset since she might flip it off the top and be forced to play it main phase anyway
Oath of Chandra - Removal for a medium sized creature, and then a little clock when I get new walkers
Hedron Archive - Mid-sized rock that can replace itself
Gilded Lotus - Big rock
Dovin, Hand of Control - Cheap walker that slows my opponents, but might be too low impact
Jace, Wielder of Mysteries - Can clear away some lands from. The top, and the ult is OK, but triple blue and only two semi-relevant is a bit thin
Ugin, the Ineffable - Card advantage and chump blockers in one ability, with the option of spot removal and making any late mana rocks cheap/free
Chandra, Flamecaller - Sweeper, self-wheel or a kind of clock, but not very efficient at sweeping or clocking for a 6-drop
Chandra, Fire Artisan - Card advantage that can remove duds from the top of the deck before combat
Chandra, Acolyte of Flame - Probably not worth a slot unless I have a significant amount of red walkers
Elspeth, Sun's Nemesis - Create chump blockers, gain some life, or even pump Narset so she might be safe to attack. Can be re-cast from the graveyard when she dies, but I doubt I will ever have 6 mana to spend on that quality of abilities
Fuel for the Cause - Doesn't do a lot if flipped by Narset, but the proliferation potential is sweet
Steady Progress, Contentious Plan - Proliferate without losing a card
Emergency Powers - Shuffle back my yard full of dead walkers, refill my hand and drop a new walker
Valakut Awakening - A land drop that can do something when flipped by Narset
Elspeth Conquers Death - Reanimate a walker some turns down the line, and get a bit of removal before that
Whispersilk Cloak - Unblockable Narset for safe attack triggers
Teferi's Time Twist - Can save Narset from a sweeper and make her come back harder to block, blink Deepglow so it comes back on the end step right before my turn, or just save a walker from a lethal attack, but since the thing doesn't come back until the end of turn, its uses are limited
Wanderer's Strike - Spot removal with a proliferate on it, but probably not worth it at 5 cmc and sorcery speed
Single Combat - Sweep the board and keep either Narset or a walker that's ready to ult, but it lasts through my NEXT turn, so I can't cast anything off of Narset trigger
Jace, the Living Guildpact - The ult is nice if I can get there, and the plus can do some filtering for Narset, but probably not worth a slot
Sarkhan, the Dragonspeaker - Another walker that can attack, and also work as spot removal, but it probably doesn't work at EDH scale
Spectra Ward - Make Narset nigh-unblockable, and turn her into a pretty good blocker herself, or just a faster clock
Hanweir Battlements

Consider (don't have):
Gatewatch Beacon
$$ Vronos, Masked Inquisitor
Serum Snare - Cheap bounce with proliferate
Jaya's Phoenix
Leori, Sparktouched Hunter
Onakke Oathkeeper
$$ Teferi, Temporal Pilgrim - Super-sweeper ult
$$$ All Will Be One
Deification - Make an important planeswalker "unkillable", e.g. Chandras to keep producing emblems
$ Elspeth Resplendent - Make Narset bigger and evasive, then even bigger and lifelinky
$$ Arena Rector - Chump an attack and tutor for exactly the walker I need
$ Passionate Archaeologist - Get a good dose of burn on every attack
$ Gideon Blackblade - Can let Narset safely attack, can turn sideways itself, and can work as spot removal
Deploy the Gatewatch
$$$ Dack Fayden - Just a good walker that is cheap enough to cast without Narset
$ Tezzeret, Artifice Master - Chump blockers, card draw and a sweet ult that can be reached with a Deepglow while still sticking around
$$ Seize the Day - Extra combats
$$ Mu Yanling - Unblockable Narset, card draw, or even an extra turn
Will ($$) and Rowan ($) Kenrith - Rowan can sweep, and the ultimate lets me double all walker activations, while Will can make it easier to cast them from hand and also draw me extra
$$ Karn, Scion of Urza - Card advantage or decently big dudes
$$$$ The Wandering Emperor
$$ Eldrazi Conscription - Make Narset truly fearsome
$ Kazuul, Tyrant of the Cliffs - Good protection for my walkers, but creature-based
Semesters End - Flicker a bunch of walkers during an opponent's combat and get them back refreshed for my turn. Even better with Deepglow Skate
Bloodthirsty Blade, Psychic Impetus, Shiny Impetus - Goad the creature that is most likely to kill planeswalkers
Martial Impetus - Incentivize attacking elsewhere
Volt Charge - Removal with proliferate

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Possible cuts:
Irenicus's Vile Duplication - Extra Narset probably, but otherwise unlikely to do anything at all
* Lithoform Engine - Can copy either Narset trigger or a planeswalker activation, but the other abilities don't do much
Steel of the Godhead - Unblockable and lifelink for Narset
Sensei's Divining Top - Can help me draw the land or creature in my top 3 so I don't flip them off Narset, but without a lot of fetches it's not that great
Ponder - Is this worth a slot? Useful for fixing early draws, or getting a second try at having good stuff on top for Narset trigger if I see lands etc
Strionic Resonator - Do I have other triggers to copy besides Narset?
Karn's Temporal Sundering - Extra turns is not very popular, but this one can let me reset a walker or similar
Tezzeret's Gambit - Divination that proliferates, but do I need to draw two cards? A cheaper variant might be better
Whirlwind of Thought - Do I need to draw this many cards? It's a Narset card, though
Path, Swords - Do I NEED this spot removal?

Tezzeret, the Seeker - Can find The Chain Veil, Lithoform Engine or Dynamo, but would die immediately. Can also find Scroll Rack, Shaku, Resonator or Greaves, or just untap rocks and/or the The Chain Veil.
* Jace, Architect of Thought - The plus makes it slightly harder to kill my walkers, and the ult can get me some sweet stuff from my opponents' decks, but I'm not guaranteed to get anything synergistic
* Jace, the Mind Sculptor - This can brainstorm every turn, but it's very easy to kill
Jave, Unraveler of Secrets - Back breaking ult which isn't too hard to get to, but otherwise doesn't do much
Tamiyo, the Moon Sage - The plus doesn't do much, the minus COULD draw me a handful of cards, which I don't need that much, but the ult is game-winning
Teferi, Who Slows the Sunset - The plus is versatile and has some incidental life gain, while the minus gives card selection and helps clear away duds. The ult isn't important, but the extra cards are nice. The plus being able to ramp, tap down a blocker and also offload the Temporal Archmage in Chain Veil "combo" is probably enough
Teferi, Hero of Dominaria - The ultimate is amazing, and the tuck ability can be nice some times (can even be used on one of my own walkers to re-cast with Narset), but the plus is actually a bit meh because I won't be using the untapped lands
* Ral Zarek - Ramps and taps down a blocker, or helps untap the Chain Veil. If he manages to ult I will probably win, but getting there might be hard. Needed for casual Zndrsplt
Narset Transcendent - Cutting this might be blasphemy, but the plus, doesn't ALWAYS draw a card, and when it does, I have to reveal it. The minus will almost never be relevant. The ult is amazing, but requires me to plus three times
Narset of the Ancient Way - Ramps and gains a little bit of life, or digs and/or does removal, plus the ult helps me close out quicker. However, the ramp doesn't help me cast my commander, and the ult isn't exactly busted. Is cutting a Narset ok though?

Thran Dynamo - Can only get me Narset one (or maaaybe two) turns earlier, but it does make it possible to go infinite with Chain Veil
Fellwar Stone -  Might need elsewhere
Talismans - Might have too many rocks
Rogue's Passage - Colorless, but can let Narset survive combat on a full board
Reliquary Tower - Do I need no-max-handsize? Do I need it MORE than I need colors?
Interplanar Beacon - Incidental lifegain and fixing for walkers, but it's a colorless land for all other spells
Karn's Bastion - Proliferate on a land, but costs a bit to use and doesn't tap for colors
Mystic Sanctuary - Jeskai mana, but always tapped
Port Town - Will often be tapped

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Cuts:
Maze of Ith - Safe attacks for Narset, but it doesn't tap for mana at all
The Wanderer - Protects my walkers (and me) from burn, but how common is that really? No plus ability, and the minus won't always have targets. Probably not worth a slot
Counterspell - Bad flip, although it would let me protect some other spell that turn
? Venser, the Sojourner - Can get Narset a safe attack, or reset a walker, and the ult is amazing. But getting to the ult is probably hard (no immediate Deepglow ult), and a reset walker doesn't come back before the end step, so it might not survive a turn cycle. However, this can blink the Deepglow Skate, and can save something important from my own sweepers
Liquimetal Torque - Cheap rock with the possibility of making plays, but colorless, and I don't have that many things that care about artifacts
Dovin Baan - Both regular modes are somewhat useful, and if I can get the ult I should win
Time Wipe - Might not need this many sweepers
? Zariel - Dropping this turn before Narset could allow me to get a hasty attack, but it would need to stick around. If I can get to the ult I get am extra combat every turn, but I would need this to stick around and not do much for a few turns and also have Narset stick around. In which case I'm probably doing fine already
? Sword of Truth and Justice - Quickly makes Narset a very scary threat, while also proliferating and giving some evasion, but playing and equipping is quite expensive and has the potential to give no benefit. Very bad when I'm behind
Nahiri, the Harbinger - Card filtering and the spot removal is probably good enough, but maybe not? The ult doesn't really do much, although it could bring out a Deepglow Skate for double use, and people might not bother with her
Elspeth, Knight-Errant - Basically just used to give Narset evasion, at which point it could be a cheaper and less vulnerable permanent
Saheeli Rai + Felidar Guardian - This Saheeli is only here to go infinite with Guardian, which while it can reset a walker, is also mostly here for the combo
Nevinyrral's Disk - Broad sweeper that spares my walkers, but it still enters tapped when flipped by Narset
Divine Reckoning - Two sweepers that lets Narset stay alive, but everyone else also gets to keep their best thing
Mordenkainen - The dogs are nice, but none of the modes here are great
? Beacon of Tomorrows - For obvious reasons
? Norn's Annex - Protects me and my walkers, but they can always spend life to attack when it's important
? Wrath of God - Generic Sweeper
? Swiftfoot Boots - Probably won't have the mana to equip, and Narset already has hexproof
? Mystic Confluence - A counterspell that still does something if flipped by Narset, but it's so unlikely I have my single counterspell at the very moment I need it
Mystic Sanctuary - I only have like 8 islands total, so getting a trigger off of this is really hard
Call the Gatewatch - Tutor for a walker, but I don't really want them in my hand, especially after spending 3 mana to tutor