1-36 of 56 cards where the keywords include Challenger

Adroit Artificer
Affectionate Poro
Bouncer & Bolt
Boxtopus
Braum
Braum
Brutal Hunter
Cithria, Lady of Clouds
Desperate Husk
Enraged Firespitter
Fiora
Fiora
Flame Chompers!
Genevieve Elmheart
Jaull Hunters
Jayce
Jayce
Joraal
Kayn
Laurent Chevalier
Laurent Protege
Leona
Leona
Mageseeker Inquisitor
Mk0: Windup Shredder
Mordekaiser
Mordekaiser
Noble Rebel
Rhaast
Rimefang Wolf
Rune Squire
Sapling
Savage Reckoner
Scholarly Pioneer
Screeching Dragon
Sett