2056ab3d_Guide___Kings_and_Legends_Wiki__Description
[Upgrade to] Level 35 [Unlocks] Boss Fight Hard [Rewards] 2000 6 [Description] 
Boss Fights (H) can yield 'King's Equipment', up to Legendary rank cards, plus Gold and Silver! (Hard) Boss Fights are very tough... take some friends!
Game Guide - Kings and Legends Wiki
Description