Go down the stairs at the Maw’s north end, just south of the three-way bridge, to find a small underground keep that serves as the entrance to another side dungeon called Boneriven. The Soul Splitter is required to fully explore Sentinel’s Gaze.
Darksiders 2 – Sentinel Gaze
The winding stairwell that leads down into Sentinel’s Gaze is broken. Wall-run to a post where the stairs have collapsed, and then slide down. Wall-run to the left to crack open a chest, return to the post, and wall-run to the right to reach the bottom of the stairs.
You will find skeletons and skeleton warriors in the grounds surrounding the Sentinel’s Gaze vanquish them all and then run to the northeast corner of the area to find a Boatman Coin hidden inside a crate.
Go back a bit and climb the low wall near an alcove that’s blocked by Corruption crystals. Climb up to a ledge where a Shadowbomb pod grows.
Take the Relic that’s hidden behind the nearby torch, and then grab a bomb. Fall back down from the ledge and use the bomb to obliterate the alcove’s Corruption crystals so that you may access the weapon racks and chest within.
Stand near the front of the main structure. Now split up Death’s soul and climb the main structure and wall-run around its curved front wall. Keep going until you’re able to climb up to a higher ledge, where more Corruption crystals block your progress.
Switch souls and return to the Shadowbomb pod. Enter aiming mode and throw a bomb over to the soul that’s standing near the crystals. Switch souls, destroy the obstacles, and then scale the hand holds they were covering.
The hand holds lead up to the keep’s roof. Shoot the Stonebite on the back of the tall statue, and then stand on the roof’s northeast corner.
Switch souls again and chuck another Shadowbomb up to the soul on the roof. Use this bomb to destroy the crystals inside the roof’s alcove, exposing a large chest. Claim your plunder, and then optionally drop down into the hole behind the chest to visit another side dungeon called Boneriven.