New characters currently do not entice players due to the issue around levelling them. I last bought Pikel 4 months ago and he is still not in my arena team at L15. We need methods to address this if you wish to sell characters or make players excited.
- New characters start 2 levels below your max char
- Allow players to hoard spellbooks and allow them to stack to unlimited amounts for experience so that guild rallies can effectively power level
- New heroes are given innate xp buffs of 300% for a month or until 2 levels below your max hero
- Allow chests and dungeons to drop experience pots which can be hoarded for new char release
Several of these might make players happier to expand their hero pool. You should also look at some manner of controlling dungeon rewards by selecting a reward pool similar to your roster. Otherwise a 7% chance of rewards with over 12 heroes is also another reason not to recruit another hero to dilute your chances.