As long as the specified conditions are met, your rear-guard circle changes from its original state to an "astral plane" for the rest of the game. It cannot be restored back to normal unless an ability allows otherwise.
While an astral plane exists on your field, you will able to call a Star Deity to that zone, where otherwise it would have been retired and cannot even be ridden on vanguard circle. Only Star Deity can exist on that zone, and no other units can be called even with abilities.
The unit on an astral plane can attack even from the back row and perform drive checks, as well as activate its abilities. Any cards revealed by the drive check of a Star Deity on this marker go into the soul of your vanguard.
At the end of your turn, put the unit in an astral plane on the bottom of your deck.