When you discard this from play, you may exchange it for a Champion.
(This is not in the Supply.)
Hero is an Action-Traveller from Adventures. It is a terminal silver that can gain(gainer) any Treasure in the game. It is not in the Supply, but can be exchanged(exchange) for from a Warrior. Hero itself, once discarded from play, can be exchanged for a Champion. There are only 5 copies of Hero in the Hero pile.