Well now that Chimaeron is fixed and consistent I feel confident that I can give a solid 1-shot strategy to this boss that once you get it you will be able to replicate every single time. I’ve largely been dreading writing this simply because every time I’d write something one of my friends would say “yeah but what about when Chim does this” and I’d have no answer.
Chimaeron is a two phase fight and will represent one of the easier heroics you will do.
Phase 1
Much like on normal mode you will need two healers assigned to raid healing and one healer assigned to tank healing. Raid healing stays mostly the same where you are using your weak sauce mana efficient heal to heal up targets who are getting gooped.
The only healing that will get a little more intense is tank healing.
In this fight you will have a choice of either using two or three tanks with one of those being a DPS tank. The DPS tank is someone who has to be wearing plate so that’s a ret paladin, unholy DK, frost DK, fury warrior, or arms warrior.
So I will describe the two possible tank setups and you can choose which one will work for you.
Two Tank Setup:
You will have two main spec tank. One tank has to eat all breaks and the other tank has to eat all double strikes. This means that your main spec tank will need to be topped off constantly.
So one tank should be eating all breaks, this is the person tanking for the majority of the time. The other tank should be eating all double strikes.
Every now and then the robot will go offline and you will have a phase called Feud. Like in normal you deal with this by stacking up and splitting up the damage of the goop between all raid members. Nonstacked raid members will die. Your main tank should stay unstacked since the person tanking cannot get gooped.
The main tank will be the solo tank during Feud which of course will be volatile. You will need to immediately use a powerful single target cooldown on this tank. Pain suppression, shield walls, guardian spirit, lay on hands, and any other powerful single target cooldowns will be exceptionally powerful here. It will feel like your tank just gets one shot immediately if you don’t do this.
Healers should be spamming heals on raid except for the tank healer who should be nonstop spamming his most HPS efficient spells into the tank. Other raid healers can choose to aid the tank with hots, shields, and instant-casts.
There will be constant goop damage happening so you will be raid healing hard. Make sure your raid is trying to mitigate damage as much as possible. This means nether ward (warlocks), glyph of raptor strike (hunters), mage armor (hunters), feint (rogues), anti-magic shell (death knights), dispersion (priests), shamanistic rage (enhance shamans), and Barkskin/Tranquility (druids).
The double strike tank will have no break, this is why he must be the person tanking during this phase.
As soon as Feud ends the main tank has to take it back and go back to regular roles. By this time Break will have fallen off this tank.
You will go through three feuds total before second phase. If you read a fourth feud you will probably be in trouble.
Three Tank Setup:
So in this setup you will use two main spec tanks and a DPS tank. Many people who do this boss have problems dealing Break. What ends up happening is if the double strike tank doesn’t get taunted off fast enough he/she will get a stack or two of Break. This means when this tank is solo tanking during Feud will be taking bonus damage. This strat favors guilds that don’t have stamina stacking Feud tanks. Or on the other hand tanks that are not particularly geared.
In this approach your DPS tank who can be any plate wearer tanks in DPS gear and in the tanking stance/presence/aura. Because of the robot this tank cannot possibly die. As long as he’s topped up above 30%. The cool thing of course is that a lot of DPS tanks will be able to heal themselves. DPS DKs and ret paladins will do an exceptional job at this because of word of glory and death strike. DPS warriors have some moderate self heals they can use in a tight spot.
Your first main tank will soak all of the double strikes. it is permitted for your double strike tank and DPS tank to share breaks.
Your third tank will taunt the boss during Feud and tank it alone. This tank should be your highest HP tank. A feral druid will fit this role very well as he will be able to DPS while he’s not tanking. This tank will still have to be spammed just like in the 2-tank approach except you’re removing Break from the equation.
After three feuds phase 2 will begin.
Phase 2
The push for Phase 2 is an important one. The ideal phase 2 opening is having your tank with no break tanking and everyone topped off to 100%. To do this you have everyone but the tank stacking up. You will push over at 20% so make sure your DPS are stopping around 23%. You need to let that third feud happen. After that feud ends if you are close to 20% push it over. There should be enough time for your healers to top up everyone while stacked.
Your two tanks will be able to soak a lot of hits and dodge/parry a lot of them as well. You will want whoever is tanking to pop every single cooldown they have right away if they intend to survive for any amount of time. Two tanks with all cooldowns up should be able to survive about 30-45 seconds.
Once Phase 2 pushes over it’s best that you stay stacked. Logic tells you that you should spread out so that the boss traveling around will give you more time to react and kill the boss. This logic however fails when you realize that Chimaeron has a 5-second swing timer meaning that as soon as he targets you, you will have a full 5 seconds to react to him. This fight is insanely good for hunters and rogues as they will be able to Evasion and Deterrence a few swings from Chimaeron. After that they will be immediately able to vanish/feign death to interrupt his swing timer. Obviously hunters are best to spread out as they can just disengage away and will lose no DPS time.
While this phase is going on there will be a constant ticking dot from Nefarian that will take 10% of your HP every 10 seconds. After about 30 seconds you will stop getting 2-hit by Chimaeron and start getting 1-hit. Healers should be DPSing during this phase with the exception of priests. Priests can still shield players and should make every effort to get a shield up on everyone before they start DPSing. After all the shields wear off they should reapply them all. Obviously if you have anything like antimagic zone or power word: barrier this will help a lot too.
Best of luck on this kill.