Azu-Fareen

Azu-Fareen is some sort of demonic shadow dragon in the Shadowfell. Tolko appeared to be working for him.

Notes the PCs stole from Azu-Fareen
The heroes stole some of his notes from a cave where they fought him in the Shadowfell.

Azu-Fareen's Bright Return
2nd Level Conjuration (ritual)

Casting Time: 1 action

Range: Touch

Components: V, S, M (an iron bell, liberty cap mushroom worth at least 1cp eaten by the target up to an hour before spell is cast).

Duration: Instantaneous

You touch a willing creature in the shadowfell, fey wild, or ethereal plane, sending it back to the material plane. It arrives in an unoccupied space at a roughly corresponding position to where it is when the spell is cast.

Azu-Fareen's Planar Compass
1st Level Divination

Casting Time: 1 action

Range: Touch

Components: V, S, M (iron filings)

Duration: 1 Hour

You touch a willing creature. Until the spell ends, that creature is aware of the direction to the point where they last entered the plane they are currently on. If they have not traveled between planes, the spell fails.

Shadow Sight
You know the exact location of any planar portals, planeswalkers, and extraplanar entities within 120 feet of you, regardless of cover. This functions as blindsight for the purposes of any effect (including attacks) that rely on sight.

To-do list

 * Re-capture mermaid-like creatures at goblin forest test site
 * See if shadows re-capture brightly returned test subjects ✔ CONFIRMED

Motivations
The Shadows are inherently lawful. To them, there is a correct and stable order to the planes, which must not be disrupted. One tenet of this order is that creatures should stay on their native planes. When one has burrowed between planes too frequently, it is a dangerous agent of chaos and must be bound so that it cannot continue to violate the order.

Controlling them
There is a powerful construct which can destroy or control the shadows. She is said to be shadow made solid. The shadows see her as their lawful queen, and obey her will.

Powers
The shadows can move between the prime material plane and the shadowfell. They have a planar residue sense, which allows them to perceive creatures who have burrowed between planes, at a distance related to how much residue the creature has on it.