Trivia: How do you kill this unit?

[sector24]

This is my MA Jotunheim game that I was playing to write the guide. So I have all magic paths except Fire, research levels are 7-9 in all magic schools, basically unlimited resources except earth gems.

I was thinking of trying to feeblemind him with Nether Darts, and then next turn sending in a couple SCs. The problem is that he's in his capital and he's scripted to sit way in the back, so even if I put my spellcasters in the front they have to walk forward for 1 or 2 turns before they're in casting range. That gives me maybe 2 or 3 volleys of Nether Darts if they don't get jammed up in the gate before the AI scripts garbage like Astral Shield and Raise Dead, etc. I'm not even sure if he can be feebleminded.

I could definitely nail him with Horror Marks and curses out of spite, but it I'll have all his provinces in a turn or two and I can probably dominion kill him first.

Are there any weapons that instantly kill casters? Like an Elf Bane for Sphinxes? It would be good to know how to deal with this in the future even if I go around him in this game.