Go ahead, climb onto the ledge and drop off into the tunnel. Head down the corridor and push the stone face on the wall behind the barrel. Enter the massive doors, walk downstairs, grab the eightballs, go downstairs and walk outside.

Walk around the castle - witnessing some very nasty sights - and enter through either main door. Take the stairs to the second floor and kill the two Skaarj - the doors in the two alcoves that they leapt from will now be open. Enter either one; you'll come to a semi-circular hallway. Kill another two Skaarj and a door will open - go in and hit the three switches to open some inner doors. Two more Skaarj will be guarding the ledge around the inner pit - kill them and grab some goodies, but don't jump into the pit - head back to the courtyard and enter a small opening in the cliff by the crucified priests.

Shoot the wall - it leads to a passage. Follow it to a cell and then a hallway Follow the corridor to the left and carry on past the locked cell doors, going through the next door. Inside will be a Skaarj guarding an ASMD.

The two switches open the cell doors - search them for freebies, enter either of the two doors and take the ramp up. Flip the switch, and jump into the cage lift. Walk up the stairs to grab the eightball, then hop into the pit to face the Titan.