Bridge 3:
Take the left tunnel after crossing Bridge 1 & Bridge 2 and continue walking. When the tunnel ends, jump down into a new area. Here you will find the third Gem. To get out of this area, direct the essence onto the crystal and make a bridge.
[Side story: Against Extremity Near the third gem, you will find a shrunken bridge and sporangia. Lure a corrupted enthralled via the bridge to feed sporangia. Cross the newly inflated bridge to unlock the side story.]
Now go back upstairs to the cage-like structure and place all three gems. This will create an opening in the ground.
Now come back to the main area and climb the ladder opposite the ramp. Shoot the red ball hanging above the enthralled (through the opening you just created using the three gems). Lure and kill the corrupted enthralled in front of the sporangia to make the third bridge.
Cross Bridge 1, Bridge 2 & Bridge 3 to collect Mask of Ughro’ecna
Also Read: Complete Walkthrough of The Mask of Ughro’ecna