No. As with other monster races that did not receive a Dragon Magazine article, Duergar do not have additional support. They also never received a flexible stat (most races were updated to get +2 to one statistic and +2 to one of two others, but Duergar are stuck with Con and Wis only). And because they aren’t explicitly able to access Dwarf feats, they can’t do so.
It is known that the Duergar (a.k.a. Grey Dwarves, evil dwarves from the Underdark) were once slaves of the mind flayers, but then managed to break free. However, I can’t find much information on how they broke free besides that their gods Laduguer and Deep Duerra were likely somehow involved.
I only have access to 5e material; the most I can find is in Mordenkainen’s Tome of Foes, which has a small section of lore on the Duergar, but a lot of it seems like it’s from the perspective of the Duergar, their legends and beliefs rather than “what actually happened”.
I have found the following:
Their period of enslavement and the revolt against the mind flayers led by their god, Laduguer, purged the influence of the other dwarves gods from their souls and thus made them into a superior race.
— Duergar, p. 77
Two mythic figures who were long ago responsible for the duergar’s liberation (from the mind flayers, presumably) have achieved divinity in the eyes of their supplicants.
— Duergar Deities, p. 79
According to legend, Deep Duerra stole the power of psionics from the mind flayers and gifted it to her people. Her command of it was so great that she dominated a mind flayer colony and turned the illithids into her slaves. (It’s unclear if this statement has anything to do with the Duergar breaking free of their enslavement, since this could equally just be some act of revenge)
— Deep Duerra, p. 79
Also known as the Grim One, Laduguer was a mighty duergar warrior who liberated his people from the illithds. Laduguer entered into a pact with Asmodeus, pledging the duergar to an alliance against Lolth and the demons of the Abyss in exchange for which Laduguer received a spark of divinity from Abbathor himself (presumably to help with the uprising against the illithids).
— Laduguer, p. 79
So the two Duergar gods, who were just normal duergar at the time (?) helped liberate their people, effectively their equivalent of Gith and Zerthimon (but without the infighting afterwards). Also that Laduguer made deals with devils to gain divinity, which I assume was before/during the revolt, not afterwards.
Besides that, the Forgotten Realms fandom page on Duergar says this:
Eventually, they rose up against their captors and gained their freedom from the mind flayers.(9)
It appears to cite a 3e (or 3.5e?) book, but I don’t have access to that book so cannot look for more information within.
How, exactly, did the Duergar break free of the mind flayers? Do we have any more information to go on from previous editions of D&D, or is “Laduguer made deals with devils, then he and Deep Duerra somehow freed their people” the best we’ve got? Even with regards to the gith gaining their freedom, we know that red dragons of Tiamat were involved, I’m hoping there’s a bit more out there about the Duergar too…
On page 122 of MM, nothing is mentioned about the need to stay focused, and there are no words to indicate that the ability to Enlarge a sleep is a spell.
This contrasts with the invisibility action of the duergar who explicitly says that he must stay focused.
So, my interpretation is that this is a kind of innate magical ability, not a spell, and therefore would not require concentration. Is this correct or am I missing something?
So, the Duergar ability to shrink / enlarge considers a spell?
How does that combination work with the "Rabies" ability of the barbarian?
1. Can I do this after getting angry?
2. Is it canceled before I get angry?
3. Can this ability be countered?
4. Does it require concentration to maintain? (I read in a previous note that it does not require it and does not require ingredients to use)
In the module The forge of fury (Small spoiler) There is a Dery Spy creature. His statblock is on p. 234 of Tales from the yawning portal.
I'm interested in the way two of its features interact with each other, Enlarge and Sneak Attack. If the Spy qualifies for a Sneak Attack while it is Extended, do the damage dice of the sneak attack double?
The action of Enlarge of the spy duergar says:
For 1 minute, the spy magically increases in size. […] While it is enlarged, the spy is Great, doubles its damage dice in the attacks with weapons based on the Force and makes Force controls and saves shots with advantage.
His sneak attack feature says:
Once per turn, the spy can inflict additional damage of 7 (2d6) when he hits a target with a weapon attack and has an advantage in the attack roll, or when the target is within 5 feet of an ally that is not incapacitated and the Spy has no disadvantage in the attack roll.
The spy has a Shortsword attack. A Shortsword is usually a delicate weapon, which means that one can use Str or Dex to hit and damage. The block of statistics suggests that the Spy uses Dex, but it is explicitly applied to Enlarge (the spy has a mod Str +0 and a mod Dex +3).
Short sword Melee weapon attack: +5 to hit. Hit: 6 (1d6 + 3) of piercing damage, or 10 (2d6 + 3) while enlarged.