guys on restoration me and my friend gone in a shack leading underground there we found invincible enemies. they took no damage what so ever not even a rocket launcher or fist of havoc can take them out.so after researching up on this it was on the alpha but they were able to take damage but in the beta no.so after fighting and dying a lot I was able to get in the room there were loot boxes only found 2 so far.the 3 enemies In the room fire rockets they can 1 or 2 shot you.so I was wandering are they really invincible or not? please help