Duergar Resilience. The duergar has advantage on saving throws against poison, spells, and illusions, as well as to resist being charmed or paralyzed.
Sunlight Sensitivity. While in sunlight, the duergar has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.
Enlarge (Recharges after a Short or Long Rest). For 1 minute, the duergar magically increases in size, along with anything it is wearing or carrying. While enlarged, the duergar is Large, doubles its damage dice on Strength-based weapon attacks (included in the attacks), and makes Strength checks and Strength saving throws with advantage. If the duergar lacks the room to become Large, it attains the maximum size possible in the space available.
War Pick. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 6 (1d8 + 2) piercing damage, or 11 (2d8 + 2) piercing damage while enlarged.
Javelin. Melee or Ranged Weapon Attack: +4 to hit, reach 5 ft. or range 30/120 ft., one target. Hit: 5 (1d6 + 2) piercing damage, or 9 (2d6 + 2) piercing damage while enlarged.
Invisibility (Recharges after a Short or Long Rest). The duergar magically turns invisible until it attacks, casts a spell, or uses its Enlarge, or until its concentration is broken, up to 1 hour (as if concentrating on a spell). Any equipment the duergar wears or carries is invisible with it.
The "Enlarge" effect of the Duergar statblock is actually different (and much more powerful) than the Enlarge/Reduce spell. It does not require concentration.
The point about previous editions is fair though, and I do like taking a page from old source books when I can.
Its enlarge feature isnt the spell (and they cant reduce). If it took concentration it would say so like in the description of its invisibility.
How often can they turn invisible? The stat block says for up to an hour, but not how often per day.
It says it right in the description. Right after invisibility - Recharges after short (1 hr rest) or long rest (8 hr rest).
so says ye until a pissed off duergar comes knocking on your door because everytime it's mispronounced a pregnant member of their species miscarries
Are they lawful evil in monsters of the multiverse though