Boneriven

Enter Boneriven through a small hole at the top of the central structure in Sentinel's Gaze.

Kill the undead prowlers and stalkers that appear upon entry.

Locate a pressure pad in front of a locked gate. Stand on the pad until it fully raises the gate, then quickly run and roll through before it closes.

Wall run across the gap to the next area and defeat all the skeletons that spawn.

In the next room, use a bomb to destroy crystals in the southwest corner for a chest and in the northeast corner to reveal a pressure plate.

Approach the lowered gate at the north of the room and activate Soul Splitter. Send clone 1 to the pressure pad in the right alcove and clone 2 to the left alcove. Exit Soul Splitter and roll through the gate before it closes.

Follow the path to the right for a chest. Return to the main area and proceed north along the lower passage.

Wall run around the corner at the end. Kill all enemies that appear.

Observe the ramp; near the top, there's a spike with a crystal on it. Shoot the crystal for a Stone of Mystics.

Climb the ramp and grab a bomb from the alcove on the upper level.

Drop back down to the pressure plate door. Use the bomb on the nearby yellow crystals to open a new path.

Enter the new area and locate a second pressure plate. Grab the chest behind it to find the Dungeon Map.

Head to the gate and enter Soul Splitter. Have both clones activate the two pressure pads. When the gate is sufficiently raised, return to normal mode and run through.

Immediately enter the short alcove to the left after passing through the gate to find a Boatman's Coin.

Proceed into the main room and defeat the undead stalker and skeletons that attack.