Shroud

Amorphous. The shroud can move through a space as narrow as 1 inch wide without squeezing.

Shadow Evolution. If the shroud deals at least 12 necrotic damage to a creature that isn't a Construct or Undead in 1 minute or less, the shroud transforms into a shadow at the start of the turn after it last dealt damage. It uses the statistics of the shadow, except it reduces the shadow's hp by an amount equal to the damage the shroud took before it transformed.

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

Undead Nature. The shroud doesn't require air, food, drink, or sleep.

Strength Drain. Melee Weapon Attack: +3 to hit, reach 5 ft., one creature. Hit: 3 (1d4 + 1) necrotic damage, and the target has disadvantage on weapon attacks that use Strength until the end of its next turn. If a non-evil humanoid dies from this attack, a new shroud rises from the corpse 1d4 hours later.

Shadow Stealth. While in dim light or darkness, the shroud takes the Hide action.