I know that during The Twinning dungeon there is an enemy on the way to the 2nd boss that has an interruptable ability called Beserk that boosts it's damage. And if you pull big you really need to interrupt that. If you don't, even a well geared healer will have a very hard time keeping you alive. It's one of those dungeons that you may have to use a tank LB if you decided to pull big.