34 cards where the text includes “monarch” and the color identity ≤ RUW and (the card is available on Paper)

Aragorn, King of Gondor (Tales of Middle-earth Commander #5)
Archivist of Gondor (Tales of Middle-earth Commander #18)
Archon of Coronation (New Capenna Commander #192)
Azure Fleet Admiral (The Lost Caverns of Ixalan Commander #144)
Canal Courier (Conspiracy: Take the Crown #28)
Champions of Minas Tirith (Tales of Middle-earth Commander #10)
Court of Ardenvale (Wilds of Eldraine Commander #21)
Court of Cunning (Commander Legends #63)
Court of Embereth (Wilds of Eldraine Commander #24)
Court of Grace (Commander Legends #16)
Court of Ire (Commander Legends #170)
Court of Vantress (Wilds of Eldraine Commander #22)
Crimson Fleet Commodore (Commander Masters #211)
Crown-Hunter Hireling (Conspiracy: Take the Crown #50)
Crown of Gondor (Tales of Middle-earth Commander #75)
Denethor, Stone Seer (Tales of Middle-earth Commander #20)
Emberwilde Captain (Commander Legends #175)
Éomer, King of Rohan (Tales of Middle-earth Commander #52)
Fall from Favor (Commander Masters #93)
Faramir, Steward of Gondor (Tales of Middle-earth Commander #54)
Fealty to the Realm (Tales of Middle-earth Commander #21)
Forth Eorlingas! (Tales of Middle-earth Commander #56)
Kavu Monarch (Invasion #149)
Keeper of Keys (Conspiracy: Take the Crown #34)
Oath of Eorl (Tales of Middle-earth Commander #64)
Palace Jailer (Commander Masters #47)
Palace Sentinels (Commander Masters #48)
Protector of the Crown (Conspiracy: Take the Crown #21)
Regal Sliver (Commander Masters #724)
Skyline Despot (Commander Masters #254)
Squee, Dubious Monarch (Dominaria United #146)
Staunch Throneguard (Commander Masters #412)
Throne of the High City (Murders at Karlov Manor Commander #307)
Throne Warden (Conspiracy: Take the Crown #25)

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