I am getting in a entirely different problem than what i have seen in other post... Our tank is doing a fine job at kiting him, We are always getting one add... So for us the problem is... Once we bring grobbulus to around 20% health he start debuffing multiple people and it turns into a chaos... We always bring him down to around 5-10% n then we wipe everytime...
Some of the things i noticed:
1. People are running into each other when they are trying to put the cloud behind the boss.
2. We are bringing two healers.. should i bring 1 more healer?
So, Any suggestion when it comes to positioning the boss or clouds when he gets multiple people??
1 more healer couldn't hurt much, but it just sounds like people are dying in the wrong places. I usually make sure to keep him fairly close to the wall all the way around, to give the most amount of space I can to people in the middle.
Personally I find it easier with 2 healers then 3. The faster your burn him at the end the less chance for things to go wrong. If you are doing it right 2 healers will finish with plenty of mana left...and if you are doing it wrong 3 healers are not going to be able to keep people alive sitting in the poison.
This is an execution fight that there is no good solution other then practice and getting your raid members to hopefully learn more about smart placement of poisons.
Since I have done this fight with several methods I will tell you my favorite for 10 man. I start him at bottom of ramp and tank him around the room counter clockwise around entire room. First couple injections go as high up the ramp as they can. After ramp is full the first few poisons where I started tanking are gone and they start following my path. My melee are instructed to be creative when they can. There are a lot of nooks and holes around where I kite where they have time to run into one of them and pop it there and save room for the ranged.
If your guild can not cohesively work together and pick up the slack when someone makes a mistake, you are going to struggle. If people are making mistakes like dropping poo anywhere they're not supposed to, it takes a raid effort to adjust and not lose to this loot pinata.
I have never used 2 healers on this fight, though we have already said goodbye to 10man naxx after 2 weeks since 25man is just so incredibly logistically easier.
3 healers all the way through naxx until you want to start doing some of the dps race achievements. No reason not to except bragging rights. 3 healers will not help stupid though, we had one single mistake on grobbulus our 2nd week doing the 10man. That guy doesn't raid with us anymore.
Tank the boss right up against the wall.
If the MT healer gets the debuff they have to let the raid know, so that the other healer can cover the tank, or if its the raid healer so that one of the off heals/dps can pick it up for a little bit.
Last time we did it any time the healers got the debuff they'd be relatively close to the path which I tanked the boss in, thus could quickly run to where they wanted to drop it, dispel themselves, heal up then continue on.
When people start panicking is when you start dying.
If the boss is at the 5-10% mark, it shouldn't take long to get that last bit of health, thus it's not as necessary to keep up the "only drop it in this spot" tactic. If it's far enough away that the tank won't run over it, and that other raid members won't run into it then it should be OK.
Our biggest issue was when our OT kept getting the debuff. DK would taunt and run away, then I'd taunt back so that the mob spent a good 6-10 seconds running between people before actually hitting anyone. The added damage from the globs can cause problems if the healers are also getting debuff, so it's very situational.
We wiped alot like you are, then i started kiting him farther so there are bigger gaps and people don't get confused. We also had 3 healer, and one making sure the person with mutating injection didn't die from standing there to long. After a few wipes people knew where to do, just keep wiping till people know what to do, after you have it down it's easy, if your healers can 2 heal it then it will just mean you can burn boss down faster.