Duergar Theurge (5e Creature)
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Medium humanoid (dwarf), lawful evil
Cantrips (at will): mage hand, minor illusion, prestidigitation, ray of frost
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.
Morningstar. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d8 + 2) piercing damage, or 11 (2d8 + 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.
Duergar theurges are duergar wizards skilled in the use of weapons and magic alike. Duergar theurges often wear simple leather adornments decorated with arcane sigils and mystic wards, both magical and nonmagical in nature.