Stone Vigil (Hard) the level 50 one, hits tanks harder than any expert dungeon but you also don't have any tools to deal with the damage, try wall to wall pulling that trash pack of dragon enemies after the Turtle boss and see what happens, it's hilarious going from the EXPERT level 90 brand new dungeon to a level 50 dungeon and popping every defensive and still having to see the healer GCD heal the entire pull.
Somehow it feels better when you are on the verge on getting killed having to use every single tool in your kit including hp potions and anti-kb slow to not die vs stomping poor defenseless enemies you find in the level 90 dungeons.