26 cards where the card is tagged “useless-in-singleton-formats”

Assembly Hall (Mercadian Masques #286)
Bifurcate (Mercadian Masques #230)
Bloodbond March (Ravnica: City of Guilds #192)
Cabal Shrine (Odyssey #121)
Cephalid Shrine (Odyssey #75)
Clarion Ultimatum (Shards of Alara #163)
Cornered Market (Mercadian Masques #14)
Dichotomancy (Planar Chaos #38)
Doubling Chant (Magic 2012 #170)
Dwarven Shrine (Odyssey #187)
Harness the Storm (Shadows over Innistrad #163)
Hint of Insanity (Odyssey #143)
Locket of Yesterdays (Time Spiral #258)
March of Burgeoning Life (Kamigawa: Neon Dynasty #201)
Mask of the Mimic (Stronghold #37)
Mimeofacture (Guildpact #30)
Mishra, Artificer Prodigy (Time Spiral #243)
Pack Hunt (Nemesis #109)
Pattern Matcher (Core Set 2020 #234)
Pyromancer Ascension (Modern Masters 2017 #108)
Remembrance (Urza's Saga #34)
Retraced Image (Torment #46)
Secret Salvage (Aether Revolt #71)
Twinning Glass (Lorwyn #264)
Verdant Succession (Odyssey #280)
Winnow (Invasion #45)

The message was clear to Sorin—time to search for something else.