As soon as you step onto the water in Smouldering Lake you are bombarded with shots from a giant ballista. This article covers how to stop the ballista from firing on you so you can explore the watery area and defeat the Carthus Sandworm in peace. If you're looking to collect everything in the area, head over to our complete walkthrough of Smouldering Lake. Before we head to the ballista it's important to pick up an item that you can't get after you stop the ballista from firing.
Start at the Abandoned Tomb bonfire in the Catacombs of Carthus. Head through the cave ahead and into the Smouldering Lake area. Run through the water, but before you continue, head to the right of the sandworm to find a wall. The ballista can hit you from here, but that's exactly what you want. Stand in front of the wall and wait for the ballista to fire, then dodge away. The shot from the ballista will break the wall behind you and reveal a hidden item.
Collect the newly visible Speckled Stoneplate Ring, then turn around and head past the Carthus Sandworm (just run past, don't worry about fighting it) to see a long staircase that leads to the boss battle against the Old Demon King. Look to the right of the stairs to see a mountain path heading up the side of the cliff. Follow the path to the end, then head down the stairs to the left.
Light the Demon Ruins bonfire below and continue down the next flight of stairs. In the room ahead there’s a Demon Cleric to the left next to stairs heading down and four Smoldering Ghrus to the right also nest to stairs. Head down the stairs and to the right go through the corridor in the far right corner of the room. Kill the Hound-rat in the corridor, then continue down the hallway to the right, approximately halfway down the corridor. At the end of the hallway is a small room with three Hound-rats.
Head through the archway to the end of the hallway to find another Hound-rat to the left and stairs to the right. Go down the stairs, then continue right to find more stairs on your left, but before you head down, at the far right end of the next room there’s a Large Hound-rat and five smaller Hound-rats that will likely attack.
Clear them out, then go down the stairs to find half a dozen toads in the next room. Clear them out or run past them and continue up the stairs on the far side. There’s a bridge at the top with a Crestfallen Knight at the far end. Try not to fight on the bridge so you don’t have to worry about falling off.
Kill the enemy then head through the opening on the far side. Continue up the ladders ahead to find yourself near the ballista when you reach the top. There’s a large stone pillar blocking the ballista shots, but it only covers you so much. Be careful when you have to move beyond the coverage of the pillar.
Head to the left and move down to the lower area where you are mostly covered from ballista fire. At the end of the path there are two Skeleton Wheels to the right and several Skeletons to the left. Take out the Wheels first, then the normal Skeletons.
To the right of the normal Skeletons are two Skeleton Swordsmen, one of which uses poison darts so be careful here. Take them down then pull the lever directly under the large ballista ahead. This stops the ballista from shooting so you can collect all of the loot down below and kill the Carthus Sandworm in peace.