Unlucky Collapsing Tunnel

Level 3Hazard
HazardUncommonLargeRemaster
AC
18
HP
43
Speed
0 ft.
Perception
+0
Fort
+10
Ref
+10
Will
+0
Stealth
+8
Recall Knowledge DC 20 (arcana)
Disable DC 18 nature check to counteract the aura of unluck that pervades the tunnels for 1 minute, or DC 20 survival to support the tunnel ceiling properly without triggering a collapse

At the unluckiest time, the shoddily supported tunnel wall collapses in on itself and floods the tunnel with dirt and stone.