Spider no loss without Magic Spring ?

[Xev]

Had the spider down to 3k then it killed a troll with one shot.
I used 5/1 trolls. Will try it again.
With 4/1/1 i run out of mana before getting him below 6k. Will try it with stoneskin 1 (3 mana instead of 5).
I give up tries with 6 trolls + 5 jotuns. Below 10k you must heal jotuns every turn.
Important:
1. there are much more new spiders if they were attacked. I don't attack any spawned spider.
2. spider boss changes position clockwise. Attack stack should be most right at spider to get fast to new location when spider boss moves.
3. all units should stay at a position where only 2 adjacent spiders can attack.

I'm sure 5/1/1 would succeed but how to get this leadership?
Now i'm thinking about iceball. Will test it this night too.
Good luck Youpiya, i hope you find a way.