How to make sure a Hero will open with a skill?

Lets say I have a Mark of Rodgort build, with all my troops equiped with a Fiery Weapon, but a Hero being the only one able to put the hex.

How I manage to make sure he will open with Mark of Rodgort instead of wasting time using other skills? I don't mind he using other skills as long as he put the Mark first... he doesnt even need to reapply it, thou it would be nice.

just force your hero to use mark of rodgort...
to do that you open the hero skill bar and press on mark of rodgort, than he will do it as soon as he can...

Yes, and there is no other way.

You could disable all of his skills except the one you want him to use but that is a bit extreme.

All I want is to make my War to keep it stance up.. is too much for ask?

Yes they can't. Some stances like mantras are always up. But only a very few stances.