This is a Tunnels and Trolls adventure in the Castle Calahony series.
You send one person in as a scout, while the other members keep guard at the entrance. The (wo)man walks towards the black pit in the middle of the circle. The pit is about man-sized, and iron bars have been set to easy climbing down.
As you investigate it, arrows fly down. They are hidden in the rocks, and only now you detect small holes in the walls.
Go to the opponents section and roll up 5 mountain orcs. Have each of them make a L1-SR at dexterity. They all aim at your scout. You may take hits on armour, and warriors may double their armour.
You cannot attack them, and have no time to descend into the pit, so
fly back to the cleft. From there you return
to the camp.