(Hero - Rogue) in Heroes 4

2 Zdob

When playing as a Rogue:
I) Max out Scouting;
II) Max out Combat!

I completely agree with you, the Ranger is the key.
2 OptiMAL

The Rogue hero will be upset when the castle is captured. He will hardly be able to recapture it alone.

The Rogue hero can steal a castle while someone else is going to capture the Rogue's castle. And if the Rogue has a City Portal scroll, he will be able to help his own castle as well.
2 BASON
I also support guerrilla warfare, but only on land. Thank you very much for the advice about sailing.