The Nightmare Demon concept had been around since 2023, and was one of my more recent concepts to be shared as part of this final Doom Eternal collection of videos. Initially, the idea was aimed at being filler to bolster my video count and introduce more culmative views to the channel. It was going to be a re-hash of the original Nightmare Imp but in Doom Eternal...
But after planning the script, I came to realise that the Nightmare Imp from Doom 64 is basically just what we have as the Prowler enemy. After this realisation, I went back to the drawing board only to discover that the concept I had initially thought up wasn't any good. A previous concept that I wanted to share, The Reaper came to mind and I then wanted to see if I could blend any of its elements into the Nightmare Demons.
This ultimately was the direction I ended up taking and helped to form the pivotal half-health mechanic that defines the Nightmare Demons. Even scrapped ideas are good ideas, they always come back in some way, shape, or form.
For this new direction that I wanted to take with my Nightmare Demon concept, I felt that mimicking the design style (colour swap) of Doom 64 would be lazy, and not at all what ID Software would do. So, I reached out to my viewers and one in particular who I knew from their previous works would give justice to the artistic direction of this concept. That viewer is LordFindogask734, a creator who I am privileged to have worked with. Their previous DOOM related fan-art and concept promotional pieces always caught my eye and I knew partnering with them for this video was the right decision.
LordFindogask734 went on to go above and beyond my initial briefing and create 4 brilliantly designed Nightmare Demons for this video. Their work exceeded my expectations, and even lead to me altering the Nightmare Imp's concept, giving it crystal based attacks based on the artistic design choice they went with. So truly, thank you LordFindogask734 for helping make this possible, your work defined part of this concept.
For each Nightmare Demon variant the following is always true:
Purple and semi-transparent (like a Spectre)
After taking 50% damage, they scurry away and attack more defensively
Attacks (all) leave you irradiated
Irradiated debuff will deal health damage regardless of shield and last for 3 seconds (stacks), dealing 8 damage for duration.
Rad-Suit ignores the debuff entirely
All Nightmare Demons can teleport like the Prowler at 50% health.
Nightmare Demons are a variation of demon and do not increase health or damage but may change attack styles slightly.
With these core principals in mind, I carefully designed 3 total demons that each played around these base rules. The Nightmare Imp was the most basic, something for people to come to terms with, approachable in design, easy. Then I made the Nightmare Marauder, something that pushes what was expected by the limitations of the concept by directly altering the behaviour of the demon. Then finally, the Knight-Mare, a Nightmare Demon exclusive, once again changing expectations of what could be possible.
For every one of my concepts I aim to inspire those who view them. So creating 3 destinct versions of the same core concept, I felt was neccessary to convey a level of creativity that was befitting for the channel. Hopefully it resonates with the viewers :)
The Nightmare Demons are a concept that I created for Doom Eternal that takes what we know about existing demons and changes what you would typically expect. As this is a variant of demon and non-exclusive there are a standard set of rules each Nightmare Demon will follow.
All Nightmare Demons will inflict an Irradiated status effect when dealing damage to the player. This debuff will ignore armour and attack health directly, making it a threat for generally cautious players whilst not changing too much for less experienced players as generally, they don’t have shields. This debuff will linger for 3 seconds and deal 8 health damage over its duration. If there are multiple Nightmare Demons, the effect can stack however, not from the same demon.
Nightmare Demons will behave differently to normal demons as once they are reduced to half health, they become translucent (like a Spectre) and will avoid melee confrontations where possible. They will prioritise ranged attacks as it is often more effective at inflicting damage, and therefore the Irradiated debuff. They will also gain the ability to teleport behind the player much the same as the Prowler after half their health has been depleted.
Ultimately, the Nightmare Demon variant is not supposed to be a threat alone but in conjunction with other Nightmare Demons it will become overwhelming. Fortunately, there is a counter being the Rad-Suit which when equipped will grant immunity to the Irradiated debuff. My philosophy being these concepts is that in isolation it is not a threat, but in the hands of a talented level designer it can play into a greater design. I liken my concepts to paints that a painter can mix to create an artwork or a masterpiece depending on their skill.
The Nightmare Demons are demons that have been heavily influenced by radiation. Inspired by Doom 64’s Nightmare Imp and the lore surrounding its origin, I took it to a new level and incorporated it into Doom Eternal’s playbook. In doing so, the aforementioned is true but in addition some key characteristics about the demons will change too. I like to leave much of this open to your own interpretation however, I’ll divulge some details here.
The Nightmare Imp:
This demon will exhibit the traits of all other Nightmare Demons however, as it would become quite similar to the Prowler which already exists there would be one key difference… The Imp will leak a fog from its body that will mask its movements and rapidly shred your health and armour, dealing more damage based on the speed you’re traveling at. As the Nightmare Imp will feature crystalline appendages as part of its mutation, the fog will have sharp crystal shards all through it, dealing damage whenever you enter the cloud.
Since Doom Eternal released nearly 6 years ago (wow), the player-base has dramatically improved their skills since the ‘marauder is too hard to kill’ days. I thought it would be nice to include a new challenge for players who are used to zipping around arenas like playgrounds. This crystal fog cloud would rapidly shred through player’s health and armour based on how fast you’re moving. This would punish carelessness in the arena and force over confident players to properly prioritise.
The other key change is that instead of fire-balls, the Nightmare Imp will launch crystal shards from its body that ricochet off surfaces twice. As stated before, in the hands of a good level designer, this could prove to be deadly and catch unsuspecting players off guard.
Ultimately, the Nightmare Imp will be unchanged and I think that is for the better. At the end of the day, it’s a fodder unit and should always remain as such. Non-threatening alone but in groups it may overwhelm you.
The Nightmare Marauder:
This demon will exhibit the traits of all other Nightmare Demons however, unlike the Nightmare Imp, it will perform differently to the regular Marauder on a mechanical level. Forgoing the super shotgun, shield and hell-hound, the Nightmare Marauder is now equipped with a spiked shoulder pauldron which it will use to dash rapidly towards the player. In doing so the player will be Irradiated and be knocked backwards, too.
It’s my hope that this changes the Marauder to feel more aggressive and less restrictive as many players have complained about before. Instead of a shield, the Marauder will now perfume flames in a horizontal arc as a line of defence. It will not prevent the Marauder from taking damage but will act as a strong lingering attack that is defensive.
In addition to the aforementioned abilities, at half health all Nightmare Demons will become translucent but the Nightmare Marauder will then also create shadow clones that deal the same damage but have only 1 hit-point. This ability replaces the normal Marauder’s hell-hound and should prove to make encounters more tense.
The ideology behind this demon is to elevate the formidable nature of the Marauder in a way that fits Doom Eternal without isolating players. This change is quite drastic compared to the Nightmare Imp however, I felt it to be necessary as the demon is in the Super Heavy category. Furthermore, the Nightmare Marauder will deal more damage over-all due to the irradiation debuff and more aggressive behaviour, so to balance this the shield, I felt was no longer fair to keep. Now you can deal damage to the Marauder all the time but have to keep a fine balance between aggressiveness and retreat. It’s important to keep in mind that the Nightmare Demons can all teleport so they are generally harder to attack, too.
The Knight-Mare:
This demon is exclusively a Nightmare Demon and and an entirely original concept of mine. This idea has gone through many iterations but what’s stuck best has been a dynamic approach. Unlike regular demons, the Knight-Mare will require you to defeat it twice.
Exhibiting all the traits of a Nightmare Demon, the Knight-Mare is clad in Runic Armour made from black magic deep within Hell. This armour repels Argent Energy and as such the Unmaykr and BFG along with the Sentinel Hammer and Crucible, will have no effect. Sustained damage through rapid fire-rate (ie. Chain-gun, Combat Shotgun, Plasma Rifle) will be the only way to crack the armour.
As the armour is cracking, blood will spill out from within until the demon collapses. From the collapsed body will rise a blood soaked phantom which will attack much the same as the Summoner from Doom (2016). From this point, you must defeat the phantom within a set amount of time (15 - 30 seconds) otherwise it will re-possess the body within the armour and you will have to repeat the first part of the fight.
This demon will largely attack similarly to the Hell Knight and Dread Knight but any ground slamming attacks will jettison out sharp rocks that move outward in a shockwave. It will have less health compared to the Hell Knight but the difficulty comes in with the sustained focus it demands and alone would be a troublesome threat.
(!) These ideas are entirely my own and were created between 2021 and 2025, modified slightly in 2026 to maintain relevance. The use of AI has in no way, shape or form influence or assisted in the creation of this video or the concepts and themes shared within it. I can confirm that this video and concept was created by myself, a real human being with no external assistance from an AI Agent or tool. I outwardly revoke permission to use my concepts, content and characteristics with any Artificial Intelligence model. If you wish to expand on this concept, please ensure you give credit to myself by linking this video and ensuring Artificial Intelligence is not used in your process. This channel does not support or condone the use of AI in any creative media. All of the artwork regarding the Nightmare Demons was created entirely by LordFindogask734 and permission to use, edit, redistribute their artwork soley rests with them. I do not own the rights to any of the artwork featured on this page. Thank you. (!)