Amorphous. The shadow can move through a space as narrow as 1 inch wide without squeezing.
Shadow Stealth. While in dim light or darkness, the shadow can take the Hide action as a bonus action.
Sunlight Weakness. While in sunlight, the shadow has disadvantage on attack rolls, ability checks, and saving throws.
Devil's Sight. Magical darkness doesn't impede the venerable shadow's darkvision.
Shadow Stride (3/jour). While in dim light or darkness, as a bonus action the venerable shadow can step magically up to 60 feet in an unoccupied space in dim light or darkness it can see. Then it has advantage on its next melee attack until the end of its next turn.
Strength Drain. Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 12 (2d8 + 3) necrotic damage, and the target's Strength score is reduced by 1d4. The target dies if this reduces its Strength to 0. Otherwise, the reduction lasts until the target finishes a short or long rest. If a non-evil humanoid dies from this attack, a new shadow (CR 1/2) rises from the corpse 1d2 hours later.