36 cards where the card is tagged “cost-reducer-instant”

A-Maelstrom Muse (Strixhaven: School of Mages #A-202)
Arcane Melee (Commander 2013 #29)
A-Rowan, Scholar of Sparks // A-Will, Scholar of Frost (Strixhaven: School of Mages #A-156)
A-Rowan, Scholar of Sparks // A-Will, Scholar of Frost (Strixhaven: School of Mages #A-156)
Baral, Chief of Compliance (Aether Revolt #28)
Battlefield Thaumaturge (Journey into Nyx #31)
Case of the Ransacked Lab (Murders at Karlov Manor #45)
Cloud Key (Time Spiral Remastered #265)
Curious Homunculus // Voracious Reader (Eldritch Moon #54)
Curious Homunculus // Voracious Reader (Eldritch Moon #54)
Elminster (Commander Legends: Battle for Baldur's Gate #274)
Font of Magic (Commander Legends: Battle for Baldur's Gate #71)
Goblin Electromancer (Outlaws of Thunder Junction Commander #228)
Haughty Djinn (Outlaws of Thunder Junction Commander #99)
Izzet Steam Maze (Planechase Anthology Planes #40)
Jace's Sanctum (Commander 2019 #88)
Kaza, Roil Chaser (Outlaws of Thunder Junction Commander #232)
Maelstrom Muse (Strixhaven: School of Mages #202)
Magnus the Red (Warhammer 40,000 Commander #131)
Mana Matrix (Masters Edition IV #213)
Melek, Reforged Researcher (Murders at Karlov Manor #430)
Mindsplice Apparatus (Phyrexia: All Will Be One #63)
Mizzix of the Izmagnus (Commander Masters #348)
Mocking Sprite (Wilds of Eldraine #62)
Primal Amulet // Primal Wellspring (Ixalan #243)
Primal Amulet // Primal Wellspring (Ixalan #243)
Ral, Monsoon Mage // Ral, Leyline Prodigy (Modern Horizons 3 #247)
Ral, Monsoon Mage // Ral, Leyline Prodigy (Modern Horizons 3 #247)
Rowan, Scholar of Sparks // Will, Scholar of Frost (Strixhaven: School of Mages #156)
Rowan, Scholar of Sparks // Will, Scholar of Frost (Strixhaven: School of Mages #156)
Spectacle Mage (Strixhaven: School of Mages #235)
Spellbinding Soprano (New Capenna Commander #53)
Stenn, Paranoid Partisan (Dominaria United #221)
Storm Skreelix (Innistrad: Midnight Hunt #243)
Thunderclap Drake (Outlaws of Thunder Junction Commander #17)
Urza, Lord Protector (The Brothers' War #225)
Urza, Planeswalker (The Brothers' War #238b)
Uvilda, Dean of Perfection // Nassari, Dean of Expression (Strixhaven: School of Mages #160)
Uvilda, Dean of Perfection // Nassari, Dean of Expression (Strixhaven: School of Mages #160)
Vadrik, Astral Archmage (Innistrad: Midnight Hunt #248)
Will Kenrith (Commander Legends: Battle for Baldur's Gate #738)
Wizards of Thay (Commander Legends: Battle for Baldur's Gate #105)

This search is finished. Now the real work can begin.