Can this be done? How would you fight this? (Very Hard---No AI boost)

Far into the Bhasivas campaign. Currently being attacked from all fronts. I'm trying to take out Slaneesh to secure the east.

I'd like to try to fight this to take out as many of her 7+ stacks as possible, but I get messed up by the spells every time.

Anyways, just wanted to see if this is winnable with some of y'all's superior knowledge.

If it can't be done, I'll reload last turn and not move this army there. Wait for The Thousandfold Stillness to be back up, and try to bait her into attacking. IDK