DId you guys went first to Demonis? Before you attack Karador? I just can't take out this guy... I think i had good stats but i just can't take it

I've tryed every combination from elven units but no succsses.
Lvl 25 Mage on Hard
17500 leadership
6 Atack
8 Defence
32 Intelect
50 Rage
106 Mana