Duergar (MToF)
There are 7 entries for the Duergar, not counting their constructs (which are next.) Hold onto your hats and glasses folks, we are in for a wild ride thanks to the changes.
Duergar are dwarves that live in the underdark and have some measure of psionic powers due to mind flayer experiments. In previous lore, the Duergar were considered to be the “Drow of the Dwarves.” With all the implications that implies. This book seeks to smooth that tradition over, partially by dumping the “These are the EVIL dwarves” story on the Derro (which are aberrations now). And partially by emphasizing the mental magic angle of the Duergar, as reflected in their art styles forged from living in the underdark. This is in stark contrast with the Lolthsworn Drow, who were presumably too iconic to just get rid of, despite their baggage.
Perhaps the most interesting part of the Duergar is their unique relationship to their Psionics. While nearly every Drow has access to the same core spells (with some minor variance allowed for CR and perhaps Lolth’s blessing). Duergar as NPCs can have psionic spells or powers that are totally customized to their combat roles. Duergar are also fond of artifice, and you will see where that gets us shortly.
Edit: The Duergar Enlarge ability can now be used as a bonus action. Which allows them to fight at full strength without spending a turn of setup, should they be ambushed instead of ambushing. Presumably, this change will carry over into the MM Duergar if you are interested in toying with it.
Duergar Despot
The first Duergar entry isn’t doing WotC any favors with its name, though to be fair the name came from the old book where they were supposed to be tyrants. The Despot is some kind of CR 12 Psionic Artificer Controller that fights with their Cybernetic (Psybernetic?) body parts.
In combat, Despot relies on their multiattack to make two punches and then stomp twice in that order. While their Iron Fist can push targets up to 30’ away (not up, just away), the Despot’s 25’ of movement speed dictates that it’s often better to push them 0’ and just knock the target prone, If only so they can get the sweet extra damage on their Stomp attacks. That advice is out the window (just like the defenestrated PCs) if there is any kind of pit or trap nearby, and the Despot can cast
Stinking Cloud should they need to manufacture a trap for those purposes. Despots also have the option to spew a 100’ long flame jet should their target not get proned, or if there just happens to be two targets standing in a line. Just one attack and be replaced, and the Flame Jet should always replace a Stomp for that reason. As a particularly metal finisher, the Despot will explode when they die, which may give them reason to go down swinging in a group of enemies should the situation arise.
I would also like to point out a typo in my book: The Despot can cast
Minors Illusion. And I really,
really, don’t want to know what that spell does.
In the changeover, the Despot lost
Counterspell and
Misty Step. Additionally, their multiattack can no longer be used to just spray fire everywhere all the time. Not going to lie, I would pick fire over punches any day. But that’s kind of the point of these changes, WotC just wanted the Despot to punch with its Iron Fist so I assume we can chalk that up to normalizing the encounter.
Edit: Also, they can now move between their attacks without provoking an OA, which is handy for an extreme push into a trap.
Duergar Kavalrachni.
These are the Duergar Calvary. They are a CR2 front line breaker with an ability that allows their mount to attack whenever they land a melee attack on a target. Their weapon of choice is a poisoned War Pick that allows for the use of a shield. Their backup weapon is a heavy crossbow.
The most interesting part of the Kavalrachni is their Shared Invisibility power, which is basically the
Invisibility spell, except it also applies to their mount (and it's explicitly magical for what it’s worth.)
Their tactics should be relatively obvious: Use Shared Invisibility to get into a good position, then use melee attacks on a vulnerable enemy.
In the changeover, their mounted combat powers now apply to any mount they use, and not just female striders.
Duergar Mind Master
Despite their name, the Mind Master is more of a magically enhanced Rogue than a Mage. As such, they serve as CR 2 spies/assassins. With 30’ of truesight, they don’t even have to worry about illusions when they arise.
In combat, the Mind Master will use multiattack to stab their target with Mind-poison daggers twice. Or alternatively they can replace one of those attacks with a bit of mind control. Said Mind Mastery is a bit limited, the Mind Master can either force a reaction attack or make the target move 10’. But either way I am sure you can find uses for it.
The Mind Master can also make themselves invisible with a power that is similar to the spell, but that’s more of a redundancy thanks to their signature bonus ability: Reduce.
Reduce makes the Mind Master Tiny, gives them the ability to hide as a bonus action, and a huge bonus to both their AC and their Stealth score. It’s perhaps the ideal power for being a spy, because everyone is looking for invisible creatures, and nobody is looking for a mouse-sized dwarf.
In the changeover, the Mind Master lost a bit of damage while Reduced.
Duergar Soulblade
Continuing with the tradition of Bad names for Duergar, the Soulblade is not like the Soulknife (though it might have been based on them at one point in time). They are CR1 warriors with a custom weapon, the ability to enlarge themselves as a bonus action (in order to take up more room on a combat map and deal more damage), and the almost stock Duergar Ability to turn invisible.
The Soulbade was totally overhauled, they lost the ability to make a new blade as a bonus action, and all of their spells. In return their damage was normalized and they got a significant boost to HP. Said changes turned them into warrior types instead of rogues. And honestly, it’s for the worse. There isn’t much here that the stock Duergar in the MM can’t do. Even the default MM duergar is arguably better because they have a ranged attack for coverage, and better synergies with other warriors in this book!
Duergar Stone Guard
The Stone Guard represents a more elite warrior. Take the normal Duergar, give them better equipment, better stats, and an ability that grants advantage on attack rolls when they are in formation. It’s a CR 2 warrior 2.0, just remember to keep the formation intact.
The Stone Guard was not significantly changed.
Duergar Warlord
Finally an unambiguous name. The Warlord is a Warlord. Cr 6 style, with Psionic flavoring. They come with Enlarge and Invisibility, but their real power shines when they can use Multiattack. Multiattack allows the warlord to strike with their weapons (the hammer even has psionic bonus damage) 3 times, and then have three of their allies make a reaction attack. For another warlordy trick, they can use their reaction to boost an allies D20 roll, for a small damage cost. Use them on
The Warlord had their Scouring Instruction changed so it can be used on creatures that are immune to psionic damage, which is handy when dealing with constructs.
Duergar Xarrorn
I’m not even going to pretend like anyone knows what this name is supposed to be. I’m sure it must be some kind of ancient dwarven word that means “fire” though. Seeing as how they are Flamethrower units.
As an aside, I must say that their artwork is straight fire. Honestly, I am just shocked and amazed that such a blatant thing actually exists in D&D. It beats out that one picture of an Air cultist flying on a balloon for the sheer audacity of it. I don’t think said art existed in any book before this.
Here is a picture, they are on the left. I can say they are perhaps my new favorite individual creature.
In combat they spray fire all over their enemies, then stab them with their “lance” until it recharges.
In the changeover, the Xarrorn was not changed, for there is no need to improve upon perfection. However, I do wish they had a bit of fire bonus damage with their standard melee attack, just for flavor's sake.