Playing on L-shaped maps.

Dirty_Player seems to have meant that the chance of the ranger Kirr appearing in the Tower's tavern is too low,
and therefore you are unlikely to be able to make him your main hero.

I think Dirty Player was hinting at the fact that it's not that easy to find a strong hero because there are so many of them. The lack of a decent starting hero is a major drawback of the Tower.