I am taking on this @Lemdoran post
Yep the sounds are a good indicator in firaXcom, i won’t call it best solution but i’ll probably prefer this than a fleeing ennemy (less loot) or a berserker (actualy a berserk can be extremly cool if it’s related to ennemy type, but i’ll be sad to see every single ennemy type trying to rush me in despair suicide mission x) )
in https://forums.snapshotgames.com/t/lost-enemies-can-be-hard-to-find/553/20
Keep the solving of lost enemy there, BERSERKER was one of few FXcom concepts I actually liked. But would not limit it to muton class enemy, let say under certain conditions all aliens should be able to have adrenaline rash, colour change, new berserk yell and a charge >:-)
Wont promote FXcom much, small pic to remind claws and colour can be added to any alien 
(We can all go Berserk)
Concept art by Piero McGowan