Mark a crawler earns for killing another crawler; Donut gains none, proving her spell knew friend from foe.
Once the dust settles at The Nest, Carl checks something urgently: whether Princess Donut picked up any additional Player Killer Skulls from the mass battle formation spell that swept up friend and enemy alike.
She did not, which he calls a relief. The spell was supposed to know who their enemies were, and it seems that part, at least, worked properly. It is the first concrete reassurance that Donut did not murder her own allies when she stuffed them into the ball.
The metric that clears Donut of killing her own people.