SRD
Gift of Tounges: The Skeleton Raven can understand the literal meaning of any spoken language that it hears. Incorporeal Movement: The Skeleton Raven can move through other creatures and objects as if they were default terrain. it takes 1d10 force damage if it's turn ends inside an object. Light Sensitivity: While in bright light, the Skeleton Raven has disadvantage on attack rolls, as well as on Wisdom(perception) checks that rely on sight. Shadow Sight: Magical darkness doesn't impede the Skeleton Raven's Darkvision. Shadow Stealth: While in dim light or darkness, the Skeleton Raven can take the hide action as a bonus action.
Strength Drain. Melee Weapon Attack: +4 to hit, reach 5ft, one target. hit: 1 necrotic damage, and the target's Strength score is reduced by 1d3. The target becomes unconscious if this reduces it's strength to 0. otherwise, the reduction lasts until the target finishes a short or long rest.
Hide only when in dim light or darkness.
Shadow ravens do not normally attack other creatures; their role is to gather and observe, then report back to their master. Solitary shadow ravens, or even small flocks of them, always seek to escape attackers rather than fighting back. Even if a large flock is assaulted, it typically flies away. If a flock of shadow ravens has no avenue of escape, it may swarm attackers, using incorporeal beaks to incapacitate aggressors before flying away.
Dark places or Celestial/Magical places