The Door in the Wall

This strange effect is both a deific blessing & a
curse. On the blessing side, from time to time
a wall will appear to you with a magic door in
it. If you enter it, you will be taken to a place
in the inner astral plane that's filled with all
manner of secrets you want to know & many
desirable treasures. However, the curse is that
the door only appears at the worst times: pick
either the door or the situation.