There are multiple ways of getting heroes: Combat, retraining or in auction. The number of heroes you can own is limited and depends on your membership in the club, and if all your hero slots are full, you can not get a new one (The only exceptions are heroes gained as a reward or from a game quest). At age restart, heroes are transferred to the new age if they are not older than 150 days. Older heroes are transferred only if they have 100000 or more experience. All heores are then reset to 1000 XP.