“Heroes of Might and Magic V: Tribes of the East”

First of all, where did you get such accurate information? Yesterday, no one on Nival's official forum knew anything about it. Can you provide a link to a reliable source?
Secondly: THREE TURNS of complete invulnerability... that's deadly. Why would anyone attack with the Stalkers themselves? In that time, the hero can strike enemies five or seven times with something enhanced and then run away cheaply. And neutral creatures will be bypassed completely unnoticed.