First to start off this guide I think I should lay down some foundation, Tormented demons are VERY powerful and I wouldn't suggest killing them unless you can afford some decent gear, which I will suggest below.
Background: Tormented Demons were added into Emps on September 29, 2015. They're level 450 and can be found in the Varrock slayer dungeon. They can be acquired as a slayer task at 77 slayer and give 2,800 slayer xp each. They do not auto attack you. They use the three attack styles (melee, range, and mage) and can protect from all three attack styles also. I would suggest just turning on protect from melee and using Piety. They also surround themselves in a fire cage (picture below) like animation that will reflect damage on you that you do to them your next hit, it doesn't always work though. The last thing you need to worry about with these demons is that once their health drops below half they go into a mode called "
enrage". You will know this mode has been entered once the red skull appears above their head.
This will boost the tormented demons stats a little, but will also drop their protection prayer. A total of 4 can be spawned in the area at a time.
Inventory and Gear:You can bring Mantas if you prefer, I was using Seas because I was out of mantas. The max hit I've been hit by is a 42 so far, so keep your HP high because if it were to hit a 42 on you and then it uses it's fire cage special and you hit a 38 on them, you could be in serious trouble. I would only bring 1 prayer potion because you normally kill 4-5 demons per trip so you shouldn't need to use more than 3-4 doses. I would also bring the Dragon Halberd for its special attack which double hits on these monsters. I've been very successful with the Halberd with my max hit so far being a 42-40.
Ferocious Ring: This ring can be found from any slayer master for 150 slayer points. It will allow you to teleport to either Rellekka slayer dungeon, Varrock Slayer dungeon, God Wars Dungeon, or Slayer Tower. It has 5 uses. For this task you will want this to teleport you to the Varrock slayer dungeon.
On a side note, ranging is a really efficient way to get a couple more kills in a load. However, you must have the correct gear to do so. I would suggest full 3rd age range for your armor just for the extra defense boost, which you'll most likely want. I didn't have a full set of 3rd age range at this given moment, but I will show you what I wore. I would bring the Dark bow and dragon arrows just for the special attack, I found it very handy when killing the Demon when it was Enraged. However, if you hit it with the dark bow and it is in it's fire cage, you will get hit with both hits you hit on it with a dark bow, which could potentially be very deadly. A safe spot for them is listed below. It is found in the Southern location of the Tormented Demons.
How to get there:Varrock Way:If you're able to purchase the Ferocious ring that I explained above, it will automatically teleport you to right in front of the dungeon, so you will still need to follow the dungeon map below
If you do not have a ring follow the map below.
Lumbridge Way:First you need to teleport to Lumbridge, after that just simply follow the maps below.
Drop table:
The Crystal drops are what everyone mainly kills them for. These crystals can be used on Elemental Bows (obtained from Chaos Elemental), Abyssal Whips or Donator whips, or the Elemental Staff (obtained from Chronozon).
Enrage mode: 
Big thank you to
Charr for helping with some of the photos!
