Hey Gamers! Welcome to Cradle of Shadows, which is part of the Shadows of the Hist DLC in Elder Scrolls Online. Very fun dungeon, and can be quite difficult at points.
Below is a video that covers all the strategies for beating this dungeon.
Of note, this video is shot on Veteran and the final boss is done on Hard mode, neither of which is needed for this particular achievement, but you will need to beat the dungeon on veteran for the achievement of beating both this dungeon and ruins of mazzatun on veteran.
Hope this helps! -Damron out