Bronze: Survive until Floor 10 in Endless Mode (2,000 gold)
Silver: Survive until Floor 25 in Endless Mode (4,000 gold)
Gold: Survive until Floor 50 in Endless Mode (8,000 gold)
Unlike the description suggests, a hero is not required to play through floor 1 to the given floor sequentially, but rather a hero must complete any singular floor that is either greater than or equal to the given floor. For example, to unlock this mastery with the Warrior, you may portal to floor 55 (assuming those portals have been unlocked with one other character) and complete that floor alone.