A slightly less powerful version of True sight, at later levels (17-20) it becomes the full version of it.

At lower levels it grants:

Dark vision with an infinite range, but the further away something is the more grey and white it becomes. (100-250 no grey scale, 260-340 slight grey scale 340-500 less and less colour until the 500ft range where it becomes only greys and whites)

Perfect vision, immune to blinding effects and can see through below 3rd level illusions (at level 10 becomes 5th level spells, at level 15 becomes 7th level spells, 17-20 can see through all illusions)

While technically immortal on the age front due to being phantasmal, they usually only live too about 200 due to the covenants secrecy policy's.

Any that aren't part of the covenant are (first of all, almost none existent) hunted down so no one can use them against the covenant.

When not in their true form, they are about the size of a normal crow. when they are, they range from the the size of a crow to a hatchling dragon.

Flight speed is about 50ft while walking is 8ft. they cant really swim as much as they kind of just float around and splash.

At birth they know, common, celestial, undercommon, and whatever the **** kenku speak I cant find it for some reason.

Due to their nature and history, Formless Corvid have increased magic ability's that when boiled down comes to +3 on all magic related things. 

Phase to the ethereal plane and be able to move through objects with a thickness of at max 10ft, the only things you cant phase through is lead, and gold. While on the Ethereal Plane, you can only effect and be effected by beings in the ethereal plane. Creatures that aren't on the Ethereal Plane can't perceive you and can't interact with you, unless a special ability or magic has given them the ability to do so.. Creatures that aren't on the Ethereal Plane can't perceive you and can't interact with you, unless a special ability or magic has given them the ability to do so.

When attacked, role a d20, while you are on the ground if you roll 10 or below means you are hit and anything above misses. While in flight rolling anything below 8 hits, and anything above misses.

If the attack requires you to roll a saving throw, you can still dodge. Using the numbers before, if you succeed you dodge. If you fail, roll the saving throw. If the attack is an area of effect you will be hit regardless if the area of affect is above 15-15ft.

Weapons, armour, and other accessories, unless specifically made for a bird is unusable. Armour outside of claw ornaments, and headdress's are unusable regardless.

Potions and other such effects can be applied.