Mask of Krati
Go to the Tensay map marker to continue the mission.
The cave entrance can be missed so check carefully. Enter the cave. Do not worry. The path is linear and can't lead to anywhere else.
Reaching the end of the cave will bring you to a large round area in the cave where the Mask is kept.
Make your way towards the mask. Eliminate all the Izila or only select ones. When you reach the mask, interact with it to start a cutscene.
After taking the mask, Batari will come and find that the mask is gone.
When the cutscene is over, your next objective is to exit the cave. So make your way out and killing the enemies in your way.
Upon reaching the exit, the mission will complete.