25 cards where the cards aren’t reprints and the mana cost is greater than or equal to {3}{U}{B}{R}

The Ur-Dragon (Commander 2017 #48)
Sauron, the Dark Lord (The Lord of the Rings: Tales of Middle-earth #224)
Nicol Bolas, God-Pharaoh (Hour of Devastation #140)
Sauron, Lord of the Rings (Tales of Middle-earth Commander #4)
Lord Xander, the Collector (Streets of New Capenna #197)
Be'lakor, the Dark Master (Warhammer 40,000 Commander #6)
Nicol Bolas, Planeswalker (Conflux #120)
Conflux (Conflux #102)
The Horus Heresy (Warhammer 40,000 Commander #126)
Primeval Spawn (Dominaria United Commander #13)
Thraximundar (Alara Reborn #113)
Sedris, the Traitor King (Shards of Alara #193)
Missy (Doctor Who #8)
Nicol Bolas, the Deceiver (Hour of Devastation #205)
Crosis, the Purger (Invasion #242)
Maestros Confluence (New Capenna Commander #75)
Prince of Thralls (Shards of Alara #182)
Blood Tyrant (Conflux #99)
Glamorous Outlaw (Streets of New Capenna #190)
Meeting of the Five (Streets of New Capenna #202)
Elder Mastery (Conflux #104)
Garza Zol, Plague Queen (Coldsnap #129)
A-Glamorous Outlaw (Streets of New Capenna #A-190)
Coalition Victory (Invasion #241)
Who // What // When // Where // Why (Unhinged #120)

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