Beating Spider-boos

[Writhan]

I took out spider as level 17 mage with the current spec:

Army:
Dwarfs (High morale)
Giants (High morale)
Cannoneer (High morale)
Cyclops (Normal morale)
Evil Beholders (Normal morale)

Spells:
Flame arrow (Rank 3 ~900 damage)
Teleport

Strategi:
Nearly every single turn, I flame arrowed the spider boss. Only when I was abit overrun with spider babies, I smacked them one instead. I had my archers placed in the center of the screen, and simply kept shooting at him. Nothing special here. What I noticed however, was whenever I engaged him with a melee unit, he either hit me, or summoned new spiders. So what I did was, simply place either my dwarfs or my giants in his face, so he had a choice what to do. It didn't matter to me if he hit them, as they could take a huge beating. I never attacked him with them, I simply just placed them on defensive stance so they took less damage. Whenever he digs down, and moves to a new location, I teleported one of the tanker units (Whichever one could reach him) over to him immidiately. Worked wonders.

I tried earlier by letting him spam summon spiders (Not engaging in melee), which resulted in me getting massively overrun eventually.

Good luck though.