48 cards where the card is tagged “cost-reducer” and the color identity ≤ B and it’s legal in Commander

Accursed Witch // Infectious Curse (Shadows over Innistrad #97)
Accursed Witch // Infectious Curse (Shadows over Innistrad #97)
Blood Funnel (Ravnica: City of Guilds #77)
Bontu's Monument (Dominaria United Commander #179)
Catalyst Stone (Odyssey #297)
Cloud Key (Time Spiral Remastered #265)
Conduit of Ruin (Battle for Zendikar #4)
Convergence of Dominion (Warhammer 40,000 Commander #154)
Defiler of Flesh (Dominaria United #90)
Dream Chisel (Onslaught #308)
Embalmer's Tools (Amonkhet #227)
Emerald Medallion (Modern Horizons 3 #291)
Eye of Ugin (Modern Masters 2015 #242)
Fluctuator (Commander 2020 #241)
Foundry Inspector (Commander Masters #385)
Frogtosser Banneret (Zendikar Rising Commander #43)
Gravebreaker Lamia (Theros Beyond Death #98)
Hazoret's Monument (Dominaria United Commander #183)
Heartless Summoning (Innistrad #104)
Heartstone (Stronghold #134)
Helm of Awakening (Dominaria Remastered #224)
Herald's Horn (The Lost Caverns of Ixalan Commander #304)
It That Heralds the End (Modern Horizons 3 #9)
Jet Medallion (Modern Horizons 3 #292)
Jhoira's Familiar (Double Masters #265)
Kefnet's Monument (Amonkhet #231)
Locket of Yesterdays (Time Spiral #258)
Long-Forgotten Gohei (Modern Masters 2015 #221)
Mana Matrix (Masters Edition IV #213)
Memory Crystal (Exodus #134)
Mutated Cultist (Modern Horizons 3 Commander #53)
Mycosynth Golem (Fifth Dawn #137)
Nightscape Familiar (Dominaria Remastered #94)
Oketra's Monument (Dominaria United Commander #188)
Panoptic Projektor (Murders at Karlov Manor Commander #44)
Pearl Medallion (Modern Horizons 3 #294)
Planar Gate (Masters Edition IV #221)
Primal Amulet // Primal Wellspring (Ixalan #243)
Primal Amulet // Primal Wellspring (Ixalan #243)
Rhonas's Monument (Game Night #56)
Ruby Medallion (Modern Horizons 3 #295)
Sapphire Medallion (Modern Horizons 3 #296)
Seal of the Guildpact (Ravnica Remastered #266)
Semblance Anvil (Scars of Mirrodin #201)
Stone Calendar (Masters Edition #167)
The Immortal Sun (Commander Masters #393)
Ugin, the Ineffable (Commander Masters #811)
Undead Warchief (Planechase #44)
Urza's Filter (Invasion #318)
Urza's Incubator (Modern Horizons 3 #297)

Though this query has ended, its relics still slumber in New Argive.