Need:
Ophidian Eye - Another Curiosity
$$$$$ Fierce Guardianship - Free Counterspell
$$$$$ Dockside Extortionist - Mana

Consider (have):
Young Pyro - Chump blockers
* Mystic Sanctuary - Fetchable land that can let me redraw something I need
* Forbidden Orchard - The 1/1s shouldn't be a problem for Niv
Spire of Industry
* Star Compass - Another rock
* Pyroclasm - Sweeper
* Mission Briefing - Reuse a (counter)spell (or dig for one) and get two triggers off Niv
Sky Diamond
* Treasure Cruise - Lower power probably also means I get more time to get cards in the yard
* Electrostatic Field/Thermo-Alchemist/Firebrand Archer - More pro-active burn plan
* Narset, Parter of Veils - I don't have a lot of wheels to really push this, but it's still rough for my opponents
* Faithless Looting - Good card selection and burn spell with Niv
* Mystic Retrieval - Get back exactly what I need
* Bolt Bend - 1-mana anti-counterspell if I have Niv, and can also get some value from targeted spot removal
* Teferi, Master of Time - Loot away extra lands, but difficult to protect
* Propaganda - Staying alive
* Chain Reaction - More sweepers
Expressive Iteration
Drift of Phantasms - Tutor for Tandem Lookout (and Ophidian Eye when I have that)
Jace Wielder/Thassa's Oracle - More lab men if someone managed to set up too much lifegain
Molten Psyche - Wheel that will probably also do a chunk of damage, but the cards go into library, which can be both a good and a bad thing. Doesn't do much if people aren't holding cards, so it's bad for catching up
Harmonic Prodigy - Doubles triggers, but can also punch hard on its own if I play enough spells
Expansion // Explosion - Manasink, and alternative wincon with Ral and another copier
Narset's Reversal - Kind of a counter, but also a copier for Ral win
Prismari Command - Flexibility
Cursed Totem - Shut down powerful abilities like Yawgmoth, but also mana dorks
Ominous Seas - Make 8/8s
Metallurgic Summonings - Get loads of chump blockers
Ral, Storm Conduit - Extra damage, and a wincon with two copiers
Polymorphist's Jest - Can sweep in combination with Niv
Midnight Clock - Mana rock with a wheel
Skullclamp - With the Locust God, this draws tons of cards and gets very wide
Mizzix's Mastery - Recast all my cantrips
Aetherflux Reservoir - Can get me some life on multi-spell turns, but I'm probably too reactive

Consider (don't have):
Archmage's Emeritus - Even more draw per spell
Sorcerer Class - Loot, then if I play token generators they can be mana dorks, and the last level kills people

Cards I have but not enough copies:
Submerge (only copy in Yuriko)
City of Brass, Mana Confluence (only copies in 5C Niv)
Mystical Dispute (both copies used in modern)
Muddle the Mixture (used in Braids, and not as important when I don't have Dockside)
* Rhystic Study (might steal from Braids)

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

Might cut for meta reasons (meta too high powered):
Clear the Mind
Blasphemous Act - Not wide enough boards
Quicken - Not enough sorceries?
Thought Vessel, Reliquary Tower - Not enough use for the colorless mana, and with no hand size I can't win with Buccaneer
* Fists of Flame - Probably not a lot of attacking going on, or card draw on my turn
Cyclonic Rift - 7-mana probably not happening
Locust God - Don't need other 6-mana wincons when playing competitive
Torbran - RRR, and I probably have neither opportunity nor need to cast this
Vandalblast
* Talrand - Probably very slow token generation
Wizard Class
Storm-Kiln Artist - Mana and a threat, but easily killed and 4 mana is a lot
Negate - 2-mana might actually be too much in competitive environments
* Arcane Denial - I definitely don't want to give away cards in comp
* Windfall - I don't really want to refuel other people's hands, and I will probably have the most cards usually, so this can only be used when behind
Izzet Charm - Flexible, but overcosted for all modes
Serum Visions - Another cantrip, but sorcery speed and doesn't give selection for right now
Stubborn Denial - Half price Negate with Niv out or force spike without, but can't be cast for free and only hits spells
Chaos Warp - Answer for resolved problems
Guttersnipe - Get some damage to players when Niv triggers have to be used as removal
Star Compass - Might not have enough basics for this to be worth it over just a Diamond

Might cut for meta reasons (meta "too casual"):
Flusterstorm
Pyroblast - Maybe not enough blue decks, but at least this can be cast to cycle
* Dispel - Mostly used to win counter wars, so this can be cut if the number of blue decks is low
Back to Basics
Spell Snare - Most important targets are Dockside, Breach, Oracle and tutors
Lightning Bolt
Abrade
Grafdigger's Cage

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

Cards cut because of meta (high power but not competitive):
Mental Misstep - Not enough important 1-mana plays
Disrupting Shoal - Might not be enough low cost important spells to counter
Spell Pierce - Same reason as Daze, although this is harder to pay for, but it is also not free to cast
* Red Elemental Blast - Maybe not enough blue decks?
* Spellskite - Probably mostly going to be a counterspell for spot removal, except tutorable? Although this can also shut down aura strategies
Daze - Force spike might not be good/important enough
* Goblin Engineer - Not enough high value stuff to get back
* Phantasmal Image - While a cheap clone is nice, it's probably here mostly to copy Dockside, which I don't have

Cuts:
Laboratory Maniac - I don't have any ways to quickly empty my library, so I'm more likely to win with commander damage
Baral - Not enough things to discount