The Outer Worlds

Certain weapons cause Plasma damage. You can also add mods that will make a weapon cause Plasma damage.

You can tell if the target died from plasma damage because they will slowly burn up and turn into a pile of ash (which you can still loot!)

Do this 100 times and the achievement is yours.

Edit: Thanks to Maxumilli0n for mentioning this needs to be done on one save file. If you score some kills, but do not save, they will not apply.

I found a very good place to get this and a lot of the other achievements which require you to grind kills.

When you get to Fallbrook on the planet Monarch, you can find someone called Catherine Malin who will give you the quest ‘Slaughterhouse Clive’.

When you get to the front gates, save before entering.

1. Clear out the few enemies at the front and get the key off the leader.

2. Enter the compound and defeat the enemies in this area..

3. After a couple of rooms you will be in a large room downstairs where they keep all the live cysty pigs. All these pigs count as kills.

4. There’s another room after the pig room with enemies too.

5. Once the place is cleaned out - reload your save. Rinse and repeat.

- While using Plasma Weapons ,which will have the word Plasma in their name and have a little Red symbol, you must kill enemies and turn them into ash!
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- Sometimes the enemy will just die and not disintegrate into ashes, those kills don't count towards the achievement
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- Grinded a lot of these on the Cystypigs lol

- Remember the SAVE trick to help you grind this out faster
One trick that helps with all of the "do this X amount of times" cheevs...use the SAVE feature to RELOAD SAVES helping you grind those out easier. *However people have said that it can cause the tracker to stop going up...so if this happens, try saving after you do one run, SAVE on a new file, then RELOAD the old one. Rinse & Repeat.

All of my HD Achievement Guides for The Outer Worlds can be found here! :) (Mobile Friendly)
https://www.bradleafsfan9.com/the-outer-worlds

In this video guide I will show you how to turn 100 enemies to ash with plasma damage. Now first things first. If you started your character right off the bat with increasing the intelligence and perception attributes. The damage will for weapons will be greater. Also making this achievement easier. Another way to make this easier would be to put points into the ranged category under skills. Not to mention there are some perks called: Scanner and Revenge for increased damage to help out. Also your companions have some perks to help. Nyoka and Parvati both have the perk called: Fine Aim for increased ranged damage.

Now a little insight on the weapons. If you look at the DPS color, it will be red. Indicating plasma damage. If you can't find a plasma weapon, you can always mod one to make it plasma. Go to your workbench on your ship or wherever. Then go into the weapon you want to use under modify. Next hit RT to go into the magazine types. If you have one it will be called: Mag-2-Power. Make sure to put that on to start working on the achievement.

Now in order for this achievement to actually count, they will need to be turned into ash. It is a random chance to happen. The higher the damage the better the chance. A good spot to get kills for this would be on Monarch. Look to the South by the water. There will be a factory called: C&P Boarst Factory. Head there and once you get there make a manual save. Now go ahead and kill everything in the factory. Including all the people, pigs, robots, and don't forget the worms on the floor count as well. Once you are done reload the manual save and keep going until the progress stops.

It will be very difficult to keep track of the ones that turn into ash and the ones that don't. So keep going until the achievement tracker stops. Now this is very important. You won't get progress for the same exact enemy. So when you turn someone into ash once, it won't count again. Just keep going after the factory if you need more kills. Once the final guy you need turns into ash the achievement will pop.

Recommend you create a save at the back of groundbreaker near the mod bench. This way you can repeat your same save with all of the other kill achievements as well.

Once you have a plasma weapon ready, steal from a vendor and this will turn the entire town into enemies. If you clear the town simply fly to the next one. Rinse and repeat as needed.

The achievement unlocks after you reduce the 100th enemy to a pile of ash when killing it with a plasma weapon. Plasma weapons are denoted with a red icon in the upper right hand corner of their info panel. The earliest plasma weapon you are likely to come across is the Bolter Pistol from an enemy drop on Emerald Vale or the Plasma Carbine purchased from the T&L vending machine at the landing pad next to the town of Edgewater.

Plasma weapons can be ranged as in the previous two examples or melee like the plasma cutter. They can deliver plasma damage as an inherent feature as in the above examples. Alternatively, a ranged weapon can be converted to a plasma weapon with the Mag-2-Power mod while a melee weapon can be converted with a Mr. Power mod. All plasma weapons have the potential to reduce the target to a pile of ash but will not do so on every kill. Only kills resulting in the pile of ash count towards the achievement.

If you use a plasma weapon, you will unlock the weapon through normal gameplay. The Hunting Rifle is an enemy drop early in the game. It can be converted to a plasma weapon with a Mag-2-Power mod acquired from an enemy drop or purchased from a vendor or vending machine. It is an excellent weapon for long range kills and has a decent probability of converting the target to ash.

If you do not use plasma weapons and/or want to get the achievement out of the way early, you can grind it. The following is a recommended approach to unlock the achievement early in the game. It works for any difficulty and any character build):
--For convenience, turn on the achievement tracker. Designate this achievement as a favorite so you can track its progress.
Note 1: All kills made in sneak mode count towards the following achievement. If you want to grind for it as well, designate it as a favorite as well so you can track both it and:

--Proceed through the game until you reach the town of Edgewater. Avoid killing sprats. Continue to play until you acquire a plasma weapon. In my experience the Bolter Pistol is the one most likely to be found first. Alternatively, acquire either a Mag-2-Power or Mr. Power mod that you can use to convert a ranged or melee weapon respectively to a plasma weapon using the workbench on your ship or elsewhere in Emerald Vale.
--Once you have a plasma weapon or the wherewithal to make one, return to your ship. Equip a plasma weapon.
--Sleep till night-time. Make a manual save on the ship. Make note of it and don't over-write it until after you get the achievement.
--Return to Edgewater. Enter the main entrance and immediately exit again. This banks an auto-save. If you are playing on other than supernova difficulty, you can make a manual save just outside the main entrance instead of relying on the autosave. If making a manual save, do not overwrite the save you made on the ship.
--Double-check to make sure a plasma weapon is equipped and it is the active weapon.
--Turn left as soon as you exit back out of town and circumvent the perimeter of the town counter-clockwise. Note a Spacer's Choice poster on the wall to your left that says, "Taste the Freedom" and turn the corner.
--Shortly after you turn the corner, you will come across a number of sprats. They will be asleep and are not easy to spot. The first is near the base of a big vertical pipe running down a structure to the right. The remaining four are on an approximate line between that sprite and the corner to your front left. Crouch and approach each one.
--Optionally, invoke tactical time dilation (TTD), , for extra damage and kill each sprat (). Note that the tracker will advance for the kills resulting in piles of ashes.
--After you have killed the 5 sprites, proceed around the perimeter to the far side of town wrt the main entrance just around the corner of what is depicted as the 'junkyard' on your map. There is no need to go into the junkyard.
--Kill another 6 sleeping sprats while crouching.
--After killing as many of the 11 sprats as is convenient, reload the auto-save you banked when you entered town.
--Repeat the process killing another 11 sprats or so and reload the banked auto-save.
--Continue killing sprats around town's perimeter & reloading the banked auto-save when you run out of targets.
--Some sprats are well hidden and hard to find If you have trouble spotting them, ignore them and reload the banked auto-save before you reach the 11 count.
--Keep an eye on the tracker. When you have reduced the 100th sprat to ash, the tracker will get to 100% and the achievement will pop. Similarly, if applicable, once you get 50 sneak kills, the Never Seen achievement will also pop.
Note 2: If you, accidentally or intentionally, lose the banked auto-save (or manual save made outside the Edgewater entrance), reload the manual save you made on the ship. You will retain all progress towards the achievement. Return to town, make another banked auto-save at the entrance by entering & immediately exiting. Resume progress towards the achievement by (sneak) killing sprats around the perimeter.

Note 3: The sprats can also be killed during the day but they will be active. They are very quick so killing them is more of a challenge and it is harder to get sneak kills.