[thejeff]

If you order any shape changer to change shape in battle, they'll change shape again at the end. For those with 2 forms, this gets them back to the original. Skratti have 3, so they wind up in wolf form. Very annoying.
It's easiest to just send them in werewolf form, despite the lower paths and thus higher fatigue from buffs.
I said "leaving out the change shape" since you didn't actually list it in your initial description.

In the reverse communion, without Shrouds they won't have E9, so no reinvig. With 2 slaves most Skratti will get 25+ fatigue from Sabbath Slave, then add their buffs & fatigue from the Hag's casting. High, but probably survivable. No decent weapons or shield still leaves them vulnerable. If you want to give them Shrouds or weapons, you have to start them as Werewolves or lose the gear which puts them at 1B and 100 fatigue from Sabbath Slave.
An interesting surprise in a pinch, especially if you're defending a province with a lab and can give them some gear. Not something I'd want to use heavily.