The Tank popped up Hallow Ground and I fully restore their HP, but when their Hallow Ground effect ended the mobs just hit hard and my heals couldn't keep up and I was using both Cure I and II. Also didn't have Presence of Mind CD up as well as it was down making my heal not as a fast.
The mobs continue to hit hard as a I think we had a BLM when they got down to 20% of their HP and then the Tank was killed while I was casting Cure II and the Tank died when I was just 0.5 seconds away from casting it. The Tank had about 40% and the Tank died within 2 - 3 but not a single mob was killed yet... all the enemies pulled from the start to the entrance of the boss room was still up.
Normally I can do big pull like this, but only if the Tank works together with me instead of being all Rambo.