I've noticed a few* omissions, namely effects that let you pay an alternate cost - which can be less than the regular cost (Zombie creaturess: Rooftop Storm) or reduced by other effects (Samurai: Kentaro, the Smiling Cat).

*Yeah, so I decided to do a proper search and it bloated into more than a "few"... Sorry for the wall of text, but here you go!

You've already got Fist of Suns and Jodah, but here are some less ubiquitous ones:

Echo: Thick-Skinned Goblin

Slowly Increasing 1/turn: As Foretold

Runes: Runeforge Champion

Fist of Suns and Jodah-like: Leyline of Mutation

Alchemy, Dragons: Sarkhan, Wanderer to Shiv

Pay life instead as Activated Ability: Marshland Bloodcaster

Alchemy, cards you don't own 1/turn: Grenzo, Crooked Jailer

From Exile 1/turn: Charred Foyer / Warped Space

Colorless 1/turn: Darksteel Monolith

Creature from exile 1/turn: Tlincalli Hunter

Conditional, Cycling: New Perspectives

Pay life instead 1/turn: Cramped Vents / Access Maze

Additionally, other regular omissions:

Flash: Cunning Nightbonder

Instants and Sorceries: Voracious Reader  ^Flip

Creature spells: Krallenhorde Howler  ^Flip, Honest Rutstein

One Giant: Invasion of the Giants

Target me! (auras, buffs, mutate): Spellwild Ouphe, Elderwood Scion

First Kicked: Vine Gecko

Historic: Ballad of the Black Flag

Not your turn: Geyser Drake

Aura and Equipment: Golden-Tail Trainer

Next Spell (honorable mention?): Hardened Berserker, Saheeli, the Gifted

Pay counters instead: Mutated Cultist

Dragons: Nogi, Draco-Zealot

Alchemy, Dinosaurs: Scalespeaker Shepherd (Not sure why is isn't linking, but I promise it exists)

Alchemy, from graveyard: Shellfish Scholar

Instants and Sorceries MV5+: Spectacle Mage

Prepared: Uvilda, Dean of Perfection  ^Flip

Undaunted keyword: Durnan of the Yawning Portal

First instant/sorcery, conditional: Eluge, the Shoreless Sea, God-Eternal Kefnet

Alchemy, Goblin: Goblin Influx Array

Next instant/sorcery (honorable mention?): Maelstrom Muse

Face-down: Panoptic Projektor

Doctors: The Eleventh Hour

Cards from exile: Commander Liara Portyr

Next instant/sorcery, conditional: Elminster

Spells you don't own: Gonti, Canny Acquisitor