Duergar Soulblade

The duergar has advantage on saving throws against poison, spells, and illusions, as well as to resist being charmed or paralyzed.

As a bonus action, the duergar can create a shortsword-sized, visible blade of psionic energy. The weapon appears in the duergar's hand and vanishes if it leaves the duergar's grip, or if the duergar dies or is incapacitated.

While in sunlight, the duergar has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.

Melee Attack Roll: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) force damage, or 10 (2d6 + 3) force damage while enlarged. If the soulblade has advantage on the attack roll, the attack deals an extra 3 (1d6) force damage.

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.

The duergar magically turns invisible for up to 1 hour or until it attacks, it casts a spell, it uses its Enlarge, or its concentration is broken (as if concentration on a spell). Any equipment the duergar wears or carries is invisible with it.

The duergar's innate spellcasting ability is Wisdom (spell save DC 12, +4 to hit with spell attacks). It can innately cast the following spells, requiring no components:

At will: blade ward, true strike

3 each/day: jump, hunter's mark