[Breschau]

I may be wrong (by no means an expert on this sort of thing) but I think you'd have needed one or two "attack one turn" before your hand of death - otherwise you'd be out of range. If you're not in range the AI will look at your choice of spell, see that it can't hit the enemy from here, and pick a different spell instead - it won't move closer unless none of its available spells/attacks are in range or you've explicitly told it to. Ideally you give the unit flying so it closes the gap with a single turn of attacking, then it can start throwing out the close range spells.

Don't think most people risk their pretenders in the arena though, the prize isn't worth it.