Problems with Heroes of Might and Magic IV.

Here's a question: has anyone used a thief as a saboteur in Heroes IV?

Yes, I did, when playing with the Human faction. /topic/at/105494/
There was also an instance in a multiplayer game. I cleared the map, and only one castle remained with a neutral hero (very strong and with a considerable army). Although I had about 5 castles, I couldn't capture his city. All mines were mine, but he still constantly received resources and bought troops. So, I placed a leveled-up Thief near his castle and gathered my main army not far from him. His hero would come out to fight my main army, I would capture his city, move the Thief away, and buy the newly available units. The AI had to return to retake the city. In this way, he didn't replenish his army and couldn't leave the city. A month passed after which I managed to defeat him, albeit with difficulty.