I was told by a friend that he was attacked by Ghouls in his Vault. I first thought it isn't quite true.
But then, I saw this, while scrolling in the Statistics:
So, how are they possible? From which population and what is the rarity of them?
P.S.: I didn't saw anything on the Wikia or the Gampedia related to this.
Best Answer
Feral Ghoul attacks like a Raider/Deathclaw attack. They come up to your vault door, claw it open, and cause damage along with radiation damage.
They are not as deadly as Deathclaws, but are definitely worse than Raiders due to the radiation damage.
You can watch a Feral Ghoul attack here: