1-28 of 28 cards where the description includes “challenger”

Camphor, the Doubt
Cithria, Lady of Clouds
Confront
Diana
Diana
Dragonguard Lieutenant
En Garde
Entrancing Lure
Fleetfeather Tracker
Jayce
Jayce
Kadregrin the Ruined
King Jarvan III
Laurent Chevalier
Laurent Duelist
Lee Sin
Lee Sin
Lee Sin's Sonic Wave
Lucky Find
Mageseeker Persuader
Petricite Broadwing
Royal Decree
Royal Decree
Shyvana's Confront
Sonic Wave
Spider Queen Elise
Tattered Banner
The Grand Plaza