Credit: Planet-Spatulon's galaxy egg (DevianArt)

An astral dragon has grown comfortable enough with your existence to grant you the ability to settle into it's beloved astral astral sea. It created and lets you shape a small demiplane within th astral sea to use as a dimensional beacon; which you can access by focusing on this piece of the astral dragon's eggshell. With it, you can potentially travel the planes like this majestic creature, and potentially meet it in your beloved astral beacon.

You can use this item by focusing for a minute (as if concentrating on a spell), after which a portal opens in the nearest unoccupied space. The portal remains open for 1 minute or until you close it (no action required). It can be up to 30 feet in diameter and leads to your planar beacon, within the astral sea.

Your planar beacon takes the shape of a 40-foot radius sphere of star filled, misty and colorful void. This demiplane mimics the astral sea, granting it particular rules:

Timeless space. As time almost doesn't affect things on that plane, creatures here don't need food nor air, don't age and can't heal nor die.

Realm of thought and imagination. This plane is tied to your thoughts and imagination. You can shape the plane with your mere thoughts, modifying it's gravitational direction, it's landscape's appearance and creating or modifying structures and inorganic materials to compose the demiplane, although such creations must fit in 20-foot radius spheres and can only exist as long as they remain on this demiplane. The modifications occur too slowly to trap creatures or cause harmful effects.

Speed of mind. Creatures on this demiplane have a flying speed equals to five times their intelligence score.

Cosmological shift. When you are on this demiplane, you can instantly open a portal to a teleportation circle or another location you know on any plane of existence.

Xenophobic The demiplane naturally reacts to intruders. If an unwilling or unwanted creature stays in this demiplane, it can attempt to exit through portals you open that are linked to the demiplane or through magical means. If it remains, it is banished to it's home plane after 48 hours.

Once you use this object, you can't use it again until you finish a long rest.