With Admonition ramping things up, the hints of new enemies, I would like to suggest some that fit into the current direction of the game.
Frankly, I am not particularly interested in Genestealers, I do not see the value in making a whole new faction; it means having to remake the same basic enemy types, which limits the amount of time that can be spent making new, more meaningful enemies.
So here are some ideas. My goal with these was to play with existing mechanics, to add new dynamics to gameplay and to mess with existing player strategies.
Elite Enemies
Plaguebearer
Infested Armor
Heralded by their morose counting chant. This could be in audible words, or could be some kind of alternate Nurglish talk - the cadence should be the giveaway of their presence, and their chanting is only interrupted when they are heavily staggered or killed.
The idea here is that these guys are slabs of meat. They move slowly, attack slowly. Their hits are not “Crusher overhead” level, but they are hard to block and give you Corruption on hit. Their heads are a weak spot, but they take less damage to this weakspot than other enemies - the goal here is to make finesse weapons (which typically are very strong) a little weaker against them. Perhaps capping the amount of bonus weakspot damage you can get against them to something like 1.5? I mean, sure, a Dueling Sword stabbing into your brain is very dangerous, but not so much if you’re a big slab of Nurglish flesh.
They have a lot of health, and pressure you just through being hard to get rid of. This should be the kind of enemy that only the most powerful of hits can theoretically one-shot; like a Fury of the Faithful, heavy charged Thunder Hammer attack kind of thing.
They also need good stagger resistance. I’d say on a tier between Crushers (who we can bully fairly easily now) and Monsters. You should be able to stagger them, of course, just not easily.
By dint of being Infested, armor sundering should not have that much of an effect on them. This means that the current meta tech of fire spam is not as effective against them, and since they are not easily staggered they will continue to advance and pressure the player.
Plague Drone
Flak Armor
These could be easily signaled by a kind of sickly buzz, like a fleshy drone engine.
A new kind of elite ranged enemy, these Nurgle-corrupted flying drones can shoot bursts of gunfire at players, but can also spit an arcing blob of goo that bursts and deals corruption. They don’t move quickly, basically just hovering about slowly, but add a third dimension to ranged combat. They should slowly move towards players - or at least towards ground level - so that if they are out of ammo they eventually move to a range where they can be engaged in melee.
These should NOT fire fully automatic, because holy **** we have enough constant gunner spam already.
Special Enemies
Plague Toadlet
Infested Armor
These enemies come in, hopping around, and letting out gurgling croaks.
These are disruptive enemies. They aren’t huge, and hop around, trying to jump into players like Pox Hounds. But instead of pinning, they simply do damage and knock the player back. Also, wherever they land will create a pool of Corruption.
Basically, they are annoying. They deny spaces to the players and move erratically, forcing player focus in a way that is unique to other enemies.
You may wonder why have a smaller one, when there’s only one in the lore, but I would point you towards Boltgun, which has Lesser and Greater Plague Toads.
Rot Fly
Not sure on armor type, this could go several directions, including Carapace armor (they do, after all, have an exoskeleton) but low health, or Unarmored (if their exoskeleton is soft and spongy) or Infected, of course.
Rot Flies come in from the air, heralded by a loud buzzing. They hover over a player before swooping in and grabbing them, stabbing them with their proboscis and dealing damage/giving Corruption. This is a full disabler, but one that is very well telegraphed, and its real value is not so much in disabling players as it is drawing their attention in new directions.
The clouds of flies around the Rot Fly gives them a resistance to ranged attacks, and they are more vulnerable to melee. When they hover above you, there should be a chance to dodge (or perhaps duck?) their grab, and then you can hit them. Otherwise, they hook you with their nasty, hook-covered legs.
Another fun detail with these could be that when you kill a Beast of Nurgle it has a chance of spawning a Rot Fly from its carcass when it blows up!
Nurgling
Infested Armor
A swarm of Nurglings, about half the height of a standard enemy, come at once to attack a specific player, heralded by their giggling and cackling.
When they reach the player, they leap onto them. When a certain threshold of them is reached, slowing the player. When a threshold of them is reached, the player becomes disabled, staggering around and steered away from their team - much like the Jockey in L4D2.
To free the player, others must attack the Nurglings (or perhaps push), but it’s not that quick. And until the player reaches the threshold of being disabled, they can look down and attack the nurglings around them. Something like a grenade at your feet would be very effective.
The point of these is to upend the normal response to a Special; most of the time players want to use a strong, pinpoint weapon to eliminate the threat in one shot, in this case, because there’s a group, different responses will be needed. Spraying weapons, spread weapons, these will be good against them.
Glitchling
Infested Armor
Similar to Nurglings, they can be told apart by the staticy laughter - and its more malicious bent - and their metal parts. They attempt to move close to players, and when they do they emit something like an EMP that damages Toughness and also disables certain player tools.
What it disables is something to be figured out in testing; it could be active ability, it could be Blitzes, or it could be ranged weapons. The point is that they deprive players of tools they really like.
Monster
Plague Toad
Plague Toad
Unyielding Armor
A whole new kind of Monster enemy. The Plague Toad moves in hops and leaps, as the Chaos Spawn does when it’s far from players, but this is its main mode of movement - perhaps it has a slow walk, but that’s all.
Its only weak point is its giant, singular eye. The Plague Toad has only 3 attacks.
Back Kick - If players stand behind it, it leans onto its front legs and kicks back, dealing high damage and knocking them back, like a Beast of Nurgle’s attacks.
Tongue Attack - It looks at its target, opens its mouth, and its tongue can be seen swelling. It then shoots out quickly and bashes into them, dealing damage and knocking them back (not a huge throw, just a push). This attack should be something that you can slide under.
Once the tongue is out, it flops to the ground and is “reeled in”. It can be attacked, and if hit enough the tongue can be cut off, which causes the Plague Toad a burst of damage and causes it to thrash about. It will still attempt to use the tongue attack, but it will only spew out goo, akin to the Beast of Nurgle’s vomit.
Bite - If a player is right in front of the Plague Toad, it will open its mouth menacingly for a moment before biting them. It takes them in its mouth, chews on them for a moment, and then spits them out, giving Corruption and throwing them away. As this is telegraphed, one can dodge-dance this, but the punishment for messing up is having to get back into a good position again (plus damage). The actual grab portion shouldn’t be overly-long; I think about the amount of time a Mutant takes to throw you when it grabs you near a wall.
At a certain health threshold, perhaps 50%, the Plague Toad will spawn Plague Toadlets out of its back, the number varying by difficulty. They hop around and cause a ruckus - and that is the point of this boss. It’s not overly threatening, but it is disruptive. It attacks, knocks players about, leaps around - and even if you cut off its tongue it can vomit on you so you get the slow debuff.
Boss Enemies
Chaos Space Marine of Nurgle
Carapace Armor
Yes, I want to kill CSM. “But they’re too strong!” some might say. “They’d kill our Rejects in a second!”
There could be story reasons for this. What if this is a small band of CSM who have upset Papa Nurgle? As a result, they have been cursed by him. This can be vaguely hinted at, not said directly, as a way of making this plausible. In my mind, they have been stricken near-blind by Nurgle. I imagine he’s not in a good mood since around this time is when Guilliman burned his Garden, I believe?
They are not directly associated with the Moebian traitors or Admonition. They are simply trying to get back in Nurgle’s good graces, and they heard about what was happening on Atoma and came to try and atone for their past failures.
They can and should be dangerous. Their armor type is, of course, Carapace. Some could wield a wword in one hand and a Bolt Pistol in the other. They switch smoothly between using them.
When they attack in melee, they rev the Chain Sword, a noticeable tell, and then attack twice; one hit will break guard, so if you do not dodge that first attack the second will hit you hard.
They use the Bolt Pistol against ranged players, taking a moment to try and aim at them (semi-blind, as I suggested), and then fire a series of shots. Players should be given time to see this coming and move. If you don’t, you get hit hard.
If you attack them from behind, they will notice, turn to look at you, and then knock you away.
They could also do a charge, as the Karnak sister does, but when they do it there’s also an attack involved. So they can close distance easily, then do their two-hit combo.
There could be alternate versions, too. Perhaps one with a scythe who does very wide slashes, or uses it to hook and pull players closer for a punch. Yeah, bring back that Chaos Warrior punch.
These could be a new mission finale boss, but also in higher difficulties like Havoc and Maelstrom they could appear on their own.
Incidentally - Plague Drones are something used by CSMoN, so those would not make much sense unless these guys were added.
We all know Space Marines are the face of 40k. We also know that adding one for us to play as would absolutely wreck the game. So why not make them enemies? This is an infinite setting, and warp shenanigans allow all kinds of things, including “weakened” CSM, so that even the most ardent lore purists could accept it. They could be some splinter group, the d-listers of the CSM bands. The “Sickly Sadfaces” is my working name for their band. Whatever. They’d be fun enemies to fight and this is a game, after all.
Conclusion
Thank you for reading this far, if you have.
Fatshark, I’ve noticed you like my ideas. I’m looking for a work in the game industry, so if you wanna hire me I can send you my resume. 
