"The Will of Ashan" - "Heart of Darkness" [2nd campaign, 5th mission]

I completed this mission a long time ago, but now I have a "problem" with my hero – Arantir (level 26) has 100 vampires. Then, Dzeleba (level 23) appeared with (Combat Spirit 4 and Luck 6) and a **huge army** – I only managed to cast the "Exile" spell once, and my army was defeated. Is it possible not to attack him, and will he chase me to my castle? I'm afraid I won't have time to gather a **decent** army.