Step 1. Equip armor that could withstand a missile.
Step 2. Create giant eruption burning everything around him in a wall of flames.
Step 3. Profit.
Or if Kovreil wasn't trying to actually commit murder, he'd probably find a way to land a good, hard punch straight to the jaw. That's what he'd usually do to subdue someone -- charge, disarm, knockout. He's a general with ~15 years of training in magic, swordsmanship, and close combat every day so there are maybe two people in his world who could actually kill him.
(Follow this fire lit road if you'd like)