I’m not going to do a narrated video this time because my experience during this particular kill will be vastly different than your own. This fight is has so many avenues of variation that it’s difficult to cover all possibilities.
As usual, this isn’t meant to be a complete guide. I assume you already know the basic mechanics of this fight. Everything here is mostly geared toward tanks, though since this fight is primarily a test of healer skill, I will add what I know for other roles as well. I only have experience in the 10 man version of the encounter, so all advice in this article is catered to that raid size.
Differences between Normal and Heroic
- Yor’sahj calls out four slimes instead of three. You can still only kill one.
- Single tank fight in 10 man. You can two tank it and swap off the debuffs, but the dps requirement can be very high and the debuff isn’t all that bad.
- Two healer fight. While learning we used three healers, and it’s probably doable that way, but we preferred two healers for our kill.
- The tank should use Prismatic Elixirs and Elixirs of the Master. The boss does very little physical damage (less than 20k on me), but the real tank killer is the spell Void Bolt, which does a large amount of upfront damage and a stacking shadow dot.
- Tanks should equip Mirror of Broken Images. It’s on-use ability is ideal for this fight.
- Add the debuff Deep Corruption to your raid frames. This is primarily for healers, but it’s good for the rest of the raid to know. For some reason your own personal Deep Corruption stacks won’t show up on grid, so keep that in mind when healing yourself.
- Check out the grid on this site for possible ooze combinations and how to handle them. They also have a more complete guide available, but we found this chart the most useful.
- Use your short cooldowns often. As a druid, I would use Barkskin once I had three stacks of Void Bolt, and then Mirror of Broken Images once Barkskin wore off.
- Use big cooldowns if there is a Purple Ooze (healing debuff) active at the same time as a Blue Ooze (mana void). Healers can’t heal you with their fast cheap heals because of the debuff, but they don’t have enough mana to spam their slow, expensive heals, so this is the best time to help them out.
Black Ooze (adds)
- Ideal time to use AoE cooldowns like Berserk.
- Tanks should debuff the adds to the best of their ability.
Blue Ooze (mana void)
- Be prepared to use or ask for cooldowns, because if the Mana Void doesn’t die fast enough your healers will run out of mana completely.
Purple Ooze (healing debuff)
- Healing is very limited this phase. Paladins are almost required for this fight because their beacon will keep the tank alive without adding stacks, and Word of Glory does not add stacks either.
- This is a very good time to use a feral druid’s Tier 13 4-piece bonus, especially when combined with a few AoE damage oozes (like black, red, or green). Even if you have a feral dpsing, you might want them to go bear 15 seconds prior to when Yor’sahj absorbs the oozes and use it once it’s available.
- Some heals don’t trigger the debuff, or are rather ambiguous. Here is the list my guild accumulated. I’ve bolded the ones that are especially useful.
- Effloresence – NO STACKS
- Lifebloom – 1 stack per application.
- Rejuvenation – 1 stack on initial application
- Swiftmend – 1 stack on the person swiftmended.
- Tranquility – 1 stack per tick (i.e. a raid killer)
- Wild Growth – 1 stack for each person hit by Wild Growth
- Feral Tier 13 4-piece (unglyphed Frenzied Regen) – NO STACKS
- Leader of the Pack – NO STACKS
- Chain Heal – 1 stack on initial hit only
- Healing Rain – 1 stack upon entering. If you leave and re-enter, you gain another stack.
- Healing Stream Totem – NO STACKS
- Riptide – 1 stack on initial application
- Spirit Link – NO STACKS
- Beacon of Light – NO STACKS
- Holy Radiance – 1 stack for initial application (i.e. if it hits 4 people, 4 people get 1 stack).
- Word of Glory – NO STACKS
- Lay on Hands – NO STACKS
- Atonement – 1 stack
- Divine Hymn – 1 stack per tick (i.e. will wipe your raid)
- Echo of Light (Holy Mastery) – NO STACKS
- Holy Word: Sanctuary – 1 stack upon entering. If you leave and re-enter, you gain another stack.
- Holy Word: Serenity – 1 stack
- Lightwell – 1 stack per buff gain (i.e. when the person clicks)
- Penance – 1 stack for the whole channeled cast (i.e. not 1 per tick)
- Power Word: Shield – 1 stack (even when glyphed)
- Prayer of Healing – 1 stack
- Prayer of Mending – NO STACKS
- Renew – 1 stack on initial application
- Priest Vampiric Embrace – NO STACKS
- Deathstrike – NO STACKS
- Bloodworms – 1 stack
- Other Abilities
- Hunter Chimera Shot – NO STACKS
- Rogue Recuperate – NO STACKS
- Warlock Healthstones – NO STACKS
- Scales of Life trinket – 1 stack
- Lots of damage goes around, and everybody has to be inside the boss’s hit box. I believe hunters can still shoot from inside the hit box.
- We almost always killed yellow, so I never saw it in action much. It also does AoE damage.
- Damage based on proximity to other players. It’s only a 4 yard range, and I’d highly recommend installing a boss mod (like Deadly Boss Mods) that gives you a proximity tracker.
- Red and Green oozes are a common combination which requires you to be very close to the boss but also 4 yards away from your raid members. Set up a circle configuration around the boss beforehand, so that players will have a predefined spot to stand in that’s close to the boss but spread out.
Success in this encounter largely depends on your healers’ ability to learn the Purple Ooze mechanics. The above list of skills that don’t trigger the Purple Ooze will be useful, but I also encourage you to experiment with the trash packs that contain Purple Oozes. Even though you will only have one or two people making the ooze calls, everyone needs to know what the oozes do and how to react to them. There are so many variations to this fight that even raid leaders can’t keep all of it in their head.