27 cards where the text includes “powerstone” and the set is “bro”

Great Desert Prospector (The Brothers' War #7)
Powerstone Engineer (The Brothers' War #20)
Repair and Recharge (The Brothers' War #24)
Static Net (The Brothers' War #27)
Koilos Roc (The Brothers' War #55)
Splitting the Powerstone (The Brothers' War #63)
Stern Lesson (The Brothers' War #64)
Urza, Powerstone Prodigy (The Brothers' War #69)
Urza's Command (The Brothers' War #70)
Ashnod, Flesh Mechanist (The Brothers' War #84)
Gix's Caress (The Brothers' War #96)
Excavation Explosion (The Brothers' War #132)
Horned Stoneseeker (The Brothers' War #138)
Sibling Rivalry (The Brothers' War #152)
Visions of Phyrexia (The Brothers' War #156)
Mishra, Lost to Phyrexia (The Brothers' War #163b)
Argothian Opportunist (The Brothers' War #167)
Fallaji Excavation (The Brothers' War #178)
Arbalest Engineers (The Brothers' War #206)
Junkyard Genius (The Brothers' War #214)
Sarinth Greatwurm (The Brothers' War #220)
Cityscape Leveler (The Brothers' War #233)
Slagstone Refinery (The Brothers' War #243)
Stone Retrieval Unit (The Brothers' War #248)
Thran Spider (The Brothers' War #254)
Hall of Tagsin (The Brothers' War #263)
Geology Enthusiast (The Brothers' War #289)

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