When we were first learning the encounter, we brought in eight healers. We learned quickly that it was one healer too many, because it tipped us past the enrage timer. Eventually, we settled on using seven healers: two of them assigned to the soak tanks, the other five on the raid. Those raid healers will be called on to heal specific players and specific groups.
Spend some time beforehand spacing people out. Make sure people in the same groups are relatively close to each other so that healers can cast their AoE spells on all of them.
Our first few tries at this boss relied on splitting up the five healers and making them responsible for any Caustic Slimes that were in that group. I realized after spending many hours on it that placing healers with that kind of responsibility may not have been the best idea. Not many healers can react or respond to the dreaded three-slime scenario. If it happened to my group, I would have cast Flash Heal on two of them and then hit the third target with a Penance or a Holy Word: Serenity. Even that was cutting it close, as a Massacre would hit a second right after.
Imagine three targets in your group all hit with a Caustic Slime that drops their health down to 1. You have a maximum of maybe 5 seconds before the next Massacre or Caustic Slime reaches the group. There is little margin for error.
I'm able to catch these incoming hits on my priest and keep up said players on my own without additional help, but I realized that some members in the guild were struggling. It may been due to a simple class healing imbalance. The diverse array of spells makes priests the go-to choice, followed by paladins and shaman. Druids just seem to have the biggest difficulty; my guess is that it's due to the way HoTs and the other druid spells function. Any awesome druid healers out there willing to offer some insight on how to handle Caustic Slimes that are immediately followed up with a raid-wide Massacre?
Our renewed efforts
After that, it was back to the drawing board. It turns out the biggest thing for us that did the trick was the automatic marks that were placed on players by your boss addon of choice. We assigned one healer to look after one mark. If their mark was already above 10k health, they were free to check on and heal anyone.
Cross Priest 2
Square Resto shaman
Moon Resto shaman 2
But that's not all. Your healers need to stand in such a way that everyone is in range of each other. It wouldn't do to have one bookkeeper on the side. The problem I had was telling people where to stand. Naturally, I told the healers to stand in the middle and allow the DPS to adjust to their positions.
Check your distances. I learned that one as a form of survival. It took me a few tries before I was able to really get it. If the healers are spaced out, there is a chance that their marked target won't be in range for them. That's why we moved every healer to the middle area and made sure the crew was able to handle themselves.
Inefficient healing becomes inefficient
I received numerous tips from multiple players who suggested using fast heals against targets hit with a Caustic Slime. The trick is to get players above the 10k health mark fast. You're not casting fast heals all the time, so you don't run the risk of burning through all your mana.
Stick to casting one fast, inefficient heal for each target until the next Caustic Slime or Massacre hits. If a Massacre does hit the raid, each raid healer should heal his own designated party once or twice to get them above the 10k health mark.
Feud phases are fun!
Since your tanks actually take damage during this phase on heroic, I really advise getting every healer to hit that one tank with one healing spell each, to drive up their health to full. Have your five raid healers start healing their assigned groups. If one healer manages to get his group's health leveled off, he can swing over and help with another one.
We're on pace for four Feud phases before Chimaeron pushes into the last phase. When you get to the last phase, have a discipline priest or two begin placing shields on everyone. This is the Heroism/Bloodlust phase. Every healer starts piling on the DPS spells.
Normally, I'm the one who's offering advice and help to both newer healers and veterans. In this case, I'm not sure if I'm qualified. We're close to getting it down, though. Any additional insights or tips in the comments would be invaluable.
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