25 cards where the illustration contains “skyline”

Angelic Observer (Streets of New Capenna #1)
Armageddon (Limited Edition Alpha #2)
Barbed Spike (Modern Horizons 2 #5)
Boseiju, Who Endures (Kamigawa: Neon Dynasty #266)
Calibrated Blast (Modern Horizons 2 #118)
Castle (Limited Edition Alpha #9)
City in a Bottle (Arabian Nights #60)
Corruption of Towashi (March of the Machine #53)
Deadeye Navigator (Avacyn Restored #47)
Harbor Guardian (Mirage #266)
Illusionary Wall (Ice Age #78)
Infectious Host (Ravnica: City of Guilds #91)
Instill Furor (Ravnica: City of Guilds #134)
Mortus Strider (Gatecrash #179)
Paliano (March of the Machine Commander #62)
Path of the Schemer (March of the Machine Commander #28)
Prairie Stream (Doctor Who #886)
Reliquary Tower (Doctor Who #296)
Sabertooth Alley Cat (Ravnica: City of Guilds #140)
Saheeli, Sublime Artificer (Secret Lair Drop #534)
Seek the Horizon (Return to Ravnica #134)
Selesnya Guildmage (Ravnica: City of Guilds #252)
Shaper Guildmage (Mirage #91)
Stinkweed Imp (Ravnica: City of Guilds #107)
Viashino Fangtail (Ravnica: City of Guilds #148)

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