You have solved yet another riddle in the Great Pyramid of Ux'ner and proceed carefully onward.
This quest is available if you have completed the quest Mi Casa, Toupasa.
Starting the Quest
Talk to Almet in the Rak'tika Greatwood to begin the quest.
Speak with Y'shtola
There will be a glow around Y'shtola, indicating an instanced battle. Check on her and there will be a cutscene, and then the battle will ensue.
Solo Duty: Legend of the Not-so-hidden Temple
When you are able to move, go forward and wait for the sentinels to go past, then follow at a distance behind it, and go north when possible. Check on the Magicked Knot that appears.
When you can move again, go north. Wait for the sentinel to start moving away, and follow behind it, but hide in the notch in the wall until the sentinel goes to the right again. Go around the corner and hide in the next notch. Then when the sentinel goes to the right, go past it to the next Magicked Knot. Check on it to proceed.
Go north and you find a room with large statues. Wait for the statues to start fighting the Doubles, then go forward and check on the next Magicked Knot.
Stand on the teleporter that appears.
In the room with the toxic mist, go west, then north, then west, then west.
In the next area, go forward down the slope. After the cutscene, follow Almet and Y'shtola, and make sure to go into the side rooms with them. Keep moving forward to jump off of the edge. Afterward, follow Almet and Y'shtola, and check on the sealed door.
Up ahead, use multi-target attacks on the Eulmoran Adjutant and Ran'jit. When Ran'jit casts Embroiling Flame, stack together with the stack marker.
When Y'shtola moves to the Sealed Door, check on it to open it, then check on the Heart of Toupasa. There will be a cutscene. This one is important, so it is recommended to watch it either now or via the Unending Journey in an inn room. (Main Scenario 1 > Shadowbringers Main Scenario Quests > Legend of the Not-so-hidden Temple > Cutscene 1.)
Speak with Thancred
Talk to Thancred to complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to Almet to accept the next quest: The Aftermath. There will be a cutscene.