A place of churning creation, constant change roils and shimmers across the entirety of the Animatic Plane. Any who find their way onto the plane are instantly subsumed into it, and entirely annihilated. The few creatures that live within the plane number among the most nightmarish and impossible to understand in all the planes, as they are made of raw protomatter that shifts between possibilities in a rush of chaotic magic.
The Gilded Heart of a Star
The cosmologists that study such things agree that the Bright Star of Animatus is the unique gate to the Animatic Plane from The Prime Material. It is often speculated that it only exists as a one-way gate which churns random detritus into the boiling ocean its heat creates. Getting into the plane is impossible, as The Bright Star shoves any matter that gets close away from it with violent force so strong that it bends the sea below it.
The Body of a God
The Animatic Plane is thought to be contained within Animatus, the Prime god of Creation. The Prime deity is widely thought to care nothing for anything at all, and it is highly unlikely that the god is aware of anything which happens within it. Regardless, any that wish closeness with this Twin would find their last moments filled with lethal rapture upon visitation. It is not known if communing with Animatus is possible from within the plane, as none have ever made it into the plane to tell.