8 cards where the illustration contains “headgear”

Auratouched Mage (Ravnica: City of Guilds #1)
Clinging Darkness (Ravnica: City of Guilds #80)
Galvanic Arc (Ravnica: City of Guilds #126)
Gaze of the Gorgon (Ravnica: City of Guilds #246)
Ordruun Commando (Ravnica: City of Guilds #137)
Spawnbroker (Ravnica: City of Guilds #65)
Sundering Vitae (Ravnica: City of Guilds #185)
Telling Time (Ravnica: City of Guilds #69)

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