The Astral Realm is a strange place, populated with floating islands and ruins and inhabited by [ Angels ]. The barrier separating the Astral Realm from the Mortal Realm, where the non-Angels dwell, is difficult to cross without using Avatar projections.
The Astral Realm is difficult to reach from the Mortal Realm; you cannot merely walk or teleport from one realm to another, and without a specific exception, beings in one Realm cannot affect or interact with beings in the other. Extradimensional spaces inside the Astral Realm cannot connect out of it, and vice-versa.
The Astral Realm is hard for [ Angels ] to Avatar project out of: only when specifically summoned by an effect that can summon angels can they interact with stuff outside the Astral Realm.
Death, hunger, and fear have no meaning within the Astral Realm. Neither does gravity, but creatures with souls are pushed downwards by an unstoppable force that resembles gravity, although it's always pushing in the same direction. Unlike gravity, every creature with a soul can jump 4 more meters vertically than they normally could, and take fall damage as though they had fallen 4 fewer meters. Creatures with souls heal rapidly, healing 1 HP every 5 minutes even without assistance.
Objects and creatures without souls however, suffer from both a lack of gravity and an impermanence of inertia. Objects and creatures without souls simply released in the air quickly come to a stop. Creatures without souls who jump find theirselves hovering if they attempt to jump more than half their jump distance. Projectiles do -2 damage after the first range increment, and stop in the air after the second. Vehicles have their movement speed reduced depending on how many slower movement modes they have than the one they're using, dividing their speed by two plus that number. Thus, a ship moving All-Out would move at a quarter of the speed.
The Astral Realm uses the same dimensions the Mortal Realm does, and as such, every point in each Realm corresponds to a point in the other Realm. For example, if a creature was able to bodily enter the Astral Realm, walk 10 meters north, and go back to the Mortal Realm, it would find itself 10 meters north of its original position in the Mortal Realm.
When a creature projects an Avatar into a realm, it creates a nearly identical copy of itself in the realm, with copies of its equipment. It shares memories, personality, and Will Save results with the creature, and in its home realm it seems to be asleep. If the real creature wakes up or otherwise stops projecting its Avatar into the other realm, its Avatar and all the equipment it brought with it vanish completely.
A creature can only have one Avatar projected at a time: attempts to project a new Avatar while one already exists always fail.
It is not possible for a creature to project an Avatar into its own realm.