I just did a couple of farm runs for the Antiquities lead in normal Darkshade Caverns 2, and we didn't have enough DPS to take down the bull netch, Grobull the Transmuted, in one go. No worries, just kill a few more waves of netchlings and burn down the remaining HP the next time he hits the ground. Or so we thought.

However, right towards the end of the airborne phase, Grobull healed to almost 100% again, and we had to burn down most of the HP all over again. And failed. And had to wait for another ground phase, and saw it self heal again to almost full health before we could get any more hits in. Rinse and repeat, ten times over. Then, all of a sudden and seemingly at random, the heal was not quite as strong, and we managed to burn it down from 60% or so to zero. For the next run, we tried harder to deal a lot of damage even though it was an easy normal run, but we still had to try a few times. No wipes, no deaths, not even close, and all adds died in seconds. We just had a boss that self healed to almost full health while being untouchable, and once again it took several attempts before we saw a weaker self heal and could do enough burst damage to make the kill.

This was with a more than decent group of reasonably high CP levels. Not everyone was a super hero, but as a group we cut through every other fight in that dungeon like butter. And to make it absolutely clear: this was normal mode.

I have never noticed this boss having a self-heal before, and online guides don't seem to make any mention of it. Is this some strange side effect of the damage and spell reflection in the airborne phase? Some of the armor sets we were wearing might have been throwing some splash damage on Grobull even when he was reflecting it, but we weren't noticeably bothered by any reflected damage. One person in the group was wearing Bahraha's Curse, but how could some weird reflection of a weak self-heal make the boss regain more than 500k HP in a few seconds?

I have no idea what happened, hence this post.