Several times now I've fought some legendary creature and in the middle of the fight they suddenly mutate and heal back to full. What other effects does this mutation do? Does this mean I can't 1 shot a legendary creature with a sneak attack?

  • 1
    You can 1 shot them, but if you get them close to dead but not quite, they will regen health back. Commented Nov 15, 2015 at 6:32
  • To add to that, I've noticed when they mutate they glow different colors, usually orange or red. I wonder if they gain defense based on the type of weapon you used against them, or maybe stronger attacks. Commented Nov 15, 2015 at 20:28
  • @VanBuzzKill, from the ones I've faced so far, I've definitely noticed stronger attacks. Commented Nov 16, 2015 at 15:11
  • 2
    Fat Man. The answer on the most questions regarding Fallout 4. Commented Nov 18, 2015 at 14:20

3 Answers 3


This is all from my own observation and I don't have an official source for it. But since I play on survival and found a LOT of legendary enemies yet, they are kinda reliable.

A mutation in Fallout 4 causes the following things to happen to an enemy:

  • It will regain their health completely
  • It will get a damage boost of about ~50% (stronger enemies get more)
  • Certain enemies get a damage reduction against the damage you used most against him before mutation
  • It may get a random "perk" from a set list.

I could not find out the total amount of perks, but according to the stuff I've seen, this is what may happen:

  • Green aura: The mob deals much more radiation damage per second . Seen on a legendary glowing one at lvl 16 and a legendary ghoul at lvl 15.
  • Orange aura: The mob dealt additional DoT damage with each hit. Seen on various enemies past lvl 20. It seems to be seperated between nuclear DoT and "normal" DoT (maybe even poison DoT?), since, when I wear a power armor, some enemies which dealt huge DoT to me before barely dealt any DoT to me.
  • Red aura: The mob gets a huge damage boost to the boost he already gets. A muted watchbot almost killed me within 2 seconds when he didn't even deal half the damage before. Seen on this Watchbot ~ lvl 24.
  • Yellow aura: The mob has highly increased movementspeed. Seen on a Mr. Gutsy.
  • Nothing: The mob doesn't get an aura. Therefore, I assume it doesn't get any special perks. Not sure though, maybe it does, but a weaker version. Maybe also: The stronger the aura, the stronger the perk.
  • (Unsure!) Blue aura (???): Grants huge damage resistance to the resistance the mob already gets. Was curios, and it could survive 2 Fat Men. Seen only once on a radroach at lvl 26, seems to be extremely rare or I'm colorblind, I was quite tired when i encountered this.

This is all the information I could find out by now, maybe there is more, I'll update the answer once I know it.

  • 1
    I just found a legendary mr gutsy with a yellow aura. from what i can tell I think his movement speed has been increased, he zooms around the map now
    – l I
    Commented Nov 18, 2015 at 13:55
  • @z' I couldn't find one of those by now, but nice to know that there are still things i didn't find yet. I love bethesda games. By the way, the DoT Aura is orange, while the damaging aura is red. I was able to see one of those yesterday. The difference is small, but recognizeable if you got sreenshots. Commented Nov 18, 2015 at 14:13
  • @z' Not a problem. Of course, I'll continue to update this answer once i know something new, and everyone should feel free to update this answer themselves or at least leave a comment once they know something not mentioned in here yet. Commented Nov 19, 2015 at 13:12
  • ok I was wrong, I don't think the yellow aura makes them fast, it makes them blow up in a nuclear explosion after they die. Ran into a legendary protectron that spawned the yellow aura: i.imgur.com/urBuZNk.jpg
    – l I
    Commented Nov 21, 2015 at 15:59

To answer your last question: It is very possible to one-shot a legendary enemy. I do it all the time, and highly recommend it.

The only way they mutate is if they're still alive after having been dropped to ~50% or less health. As long as you've got a gun that can take out more than half their HP, you can avoid having to deal with the mutation.

Personally, I prefer the one-shot kill approach whenever possible. I find the Gauss Rifle to be very effective for this (currently at level 70, on default difficulty).

If your best gun can't do the whole job in one shot, but it can still knock off more than half the enemy's HP, save it for last. Work the enemy down a bit (but not to 50%) with something weaker, then finish 'em off with the big gun once their HP is within its damage-dealing capabilities.


Can't comment on other answers, but the legendary protections always die in a nuclear explosion as long as they are activated. So that could just be very frightening to have a super fast robonuke coming right for you.

  • 2
    seems that any legendary robot will explode when they die
    – l I
    Commented Nov 26, 2015 at 18:26

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