Simply, if you play on a large or very large map, taking your time, developing, and gradually clearing the entire map, collecting and visiting everything there is, you can easily reach level 23-24, even 35-40 (but that's probably already "overdoing it").
Simply, if you play an XL map with that goal in mind
taking your time, developing
level 35-40
Korbak is just an average hero, so why not use him?
Why not use Korbak? Because we are playing as the Swamp faction. And as long as there are heroes like Tazar, Bron, and Vistan in the Swamp, Korbak is completely useless!
If, however, we are playing as another faction, and there are no cool heroes, then Korbak can be taken as the main hero if needed.
