I can't remember if I had one in that battle or not. I know I used one when sieging some insane mountain pass fort, wiping out a huge chunk of the enemies most elite forces before I even got in range of the walls. I think I was rushing the vampire coast as skavenblight and just spammed a stack and a half of the thrall rats on top of the handful of elites I'd gotten, and so I was horribly short on actually good resources and just leaned into the drown-them-in-rats strategy backed up with the ranged firepower to make it work.

It wasn't a great plan, but it was a plan and it did work.