Sacrifical Bridge

When traveling between Mausolea and the Ruins of Sirus, players will have to cross an offshoot of the main lava river. This smaller river is about 20 feet in width. Along it is a stone bridge with a small altar on its southern side. A decorated knife lays on the altar. The first time the players attempt to cross the bridge, it will collapse in front of them. They will hear a low voice coming from the altar demanding a sacrifice to restore the bridge to allow them to cross. The voice instructs each of the players to take the knife, cut themselves, and let their blood spill on the altar. The bridge will be repaired once there are no more creatures who haven't done so or who haven't found an alternative way to cross the river. If a player cuts themselves with the knife, they will notice that their wound will not stop bleeding. If they do not treat the wound with at least a second-level abjuration spell, they gain an additional stack of bleeding every half hour. Healing the wound with a lower-level spell will close it only temporarily before it opens up again. 
In truth, the bridge is not destroyed, rather, a demon residing in the altar has cast an illusion that makes it seem as if the bridge has crumbled. To see through this illusion, a player must succeed on a DC 18 Wisdom (perception) or Wisdom (insight) role. They automatically see through this if they make the DC with their passive perception or insight. A player may also investigate the bridge up close. If this is an investigation without touching the caved in area, the DC is 18 otherwise it drops to 10. The illusion is only visual, so interacting physically with the bridge makes it appear as if it is simply invisable.