Duergar Ironskin (5e Creature)
From D&D Wiki
Medium humanoid (dwarf), lawful evil
Multiattack. The duergar makes two unarmed strikes.
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.
Unarmed Strike. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) bludgeoning damage, or 12 (2d8 + 3) bludgeoning damage while enlarged. This is a magic weapon attack.
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.
Deflect Missile. In response to being hit by a ranged weapon attack, the duergar deflects the missile. The damage it takes from the attack is reduced by 1d10 + 3. If the damage is reduced to 0, the duergar catches the missile if it's small enough to hold in one hand.
Some duergar follow a secretive monastic tradition that allows a supplicant to turn their skin hard like metal. These duergar ironskins are fearsome opponents, striking with powerful blows while enlarged and retreating invisibly when battle turns against them.