Magic Resistance. Sion has advantage on saving throws against spells and other magical effects if he is in dim light or darkness.

Shadesight. Magical darkness doesn't impede Sion's darkvision.

Shadowy Demise. If Sion dies, his body melts into shadow, leaving behind only equipment he was wearing or carrying.

Sunlight Weakness. While in sunlight, Sion has disadvantage on attack rolls, ability checks, and saving throws.

Spellcasting. Sion casts one of the following spells, using Charisma as the spellcasting ability (spell save DC 13):

At will: Mage Hand, Minor Illusion

1/day each: Darkness, Mirror Image, Silence

Multiattack. Sion makes one Shadow Sword attack and uses Affix Shadow or Spellcasting.

Shadow Sword. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit:14 (2d10 + 3) necrotic damage.

Affix Shadow. Sion targets a creature within 60 feet of himself that he can see. That target must make a DC 13 Charisma saving throw. On a failed save, the target has the grappled condition (escape DC 13) as its shadow wraps around it. Once the target escapes the grapple, its shadow returns to normal.

Shadow Step. While Sion is in dim light or darkness, he magically teleports up to 15 feet to an unoccupied space he can see that is also in dim light or darkness.