Getting past the bloody spider.

[oas]

I needed a quite a few tries.
Initially I used assassins and maidens, but i kept reloading because i didn't want to lose any of those.
Then I used Trolls (3), Jarls, Polar Bears, Royal Snakes and vikings.
I used the trolls, snakes and bears to attack the spider (boss). Jarl allowed me to attack twice the spider with bears. Then in the middle of the battle I also used vikings to attack her (all of my vikings died)

I defeated the spider in 11 rounds(achievement) on impossible.