This isn't a story about me, personally, but I was involved in a party while trying to level my THM.
I was in Halatali (normal) and the tank was using nothing but autoattacks and I think the occasional attack skill? He never flashed or lobbed or anything. I ended up having to tank a majority of the first third of the dungeon before the WHM and I decided to kick him. The issue wasn't that we were having a hard time or anything but it was putting a very big strain on me (interrupts and all), and the WHM. They were struggling to heal everyone. We almost wiped a few times but we eventually made it through after a new tank joined. I was so glad I wasn't healing at that moment.
