Eater of the Gods unkillable?

[Foodstamp]

Recently in an MP game my Pretender faced the "Eater of the Gods" horror.

My pretender won easily, and it said the horror had routed. He disappeared as expected and only my pretender was left on the battlefield. Now comes the strange part. My pretender sat there and seemed to still be fighting an invisible enemy. My pretender could not hit whatever it was he was supposed to be fighting, but the "invisible" opponent would hit my pretender every single round until he finally died. Is this a special feature of the "Eater of the Gods"? Or is it just a bug?