Under normal circumstances, they won't have time to react; the initiative of the demons is 13, which almost guarantees this, but you can try to kill them with fast units, for example, Imps... in this case, it won't be possible to hide them due to the acid breath.
Imps might not even reach them. If they are standing in different corners. For example, that's how it would be for me. Because my priority is still the enemy archers.
