The Black Citadel

You evoke your Spell of Invisibility and vanish. The robed figures don't notice you enter the clearing so you decide to walk a little closer for a better look at them. To your astonishment they all vanish as you get within a few metres of them. You walk over to where they were and notice a peculiar looking stone square with demonic looking designs engraved into it. There are four paths to choose from that exit the clearing.