Amorphous. As a shadow, Selathynra can move through a space as narrow as 1 inch wide without squeezing.

Avoidance. If Selathynra is subjected to an effect that allows her to make a saving throw to take only half damage, she instead takes no damage if she succeeds on the saving throw, and only half damage if she fails.

Displacement. Selathynra projects a magical illusion that makes it appear to be standing near her actual location, causing attack rolls against her to have disadvantage. If she is hit by an attack, this trait is disrupted until the end of her next turn. This trait is also disrupted while Selathyrna is incapacitated or has a speed of 0.

Feline Leap. Selathynra can leap 20 feet from a stand-still. With a 10-foot running start, Selathyrna can long jump up to 40 feet. 

Pounce. If Selathynra moves at least 20 feet straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 15 Strength saving throw or be knocked prone. If the target is prone, the displacer beast can make one bite attack against it as a bonus action.

Shadow Stealth. While in dim light or darkness, Selathynra can take the Hide action as a bonus action.

Shadow Weaponry. Selathynra’s attacks are magical. When she hits with one of her attacks, the attack deals an extra 9 (2d8) necrotic damage (included in the attack).

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

Multiattack. Selathynra makes three attacks, only one of which can be with her tentacles. Alternately, she makes one attack with her tentacles and takes the Dodge action. 

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) piercing damage plus 9 (2d8) necrotic damage.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) slashing damage plus 9 (2d8) necrotic damage, and the target's Dexterity score is reduced by 1d4. The target dies if this reduces its Dexterity to 0. Otherwise, the reduction lasts until the target finishes a short or long rest.

Tentacles. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 8 (1d6 + 5) bludgeoning damage plus 3 (1d6) piercing damage plus 9 (2d8) necrotic damage.

If a fey creature dies from this attack, a shadow rises from its’ corpse and acts immediately after Selathynra in the initiative count. The shadow is under Selathynra’s  control.