Yor'sahj is just like many other encounters within the zone, requiring two tanks, five to six healers, and a good mix of both melee and ranged DPS. The boss will be tanked right where he stands and there isn't all that much movement to the encounter. There is potentially some AOE, so do bare that in mind. For most of the encounter, the raid will want to remain stacked on top of Yor'sahj, only spreading out when an ability calls for it.
- Void Bolt Deals moderate shadow damage plus additional shadow damage over time. The DOT effect can stack.
- Fusing Vapors Blood globules emit a fusing vapor when damaged below 50% health that heals all other active globules for 5% health. When one globule dies, all surviving globules gain immunity to all forms of damage.
- Yellow Globule Infuses Yor'sahj with Glowing Blood allowing Void Bolt to hit all nearby targets for moderate shadow damage, all abilities are used twice as often, and attack speed is increased by 50%.
- Blue Globule Allows Yor'sahj to summon Mana Voids, these leech all mana from every target in the area, storing the mana. Killing the Void releases the mana back to all players within 30 yards.
- Red Globule Grants the Searing Blood ability. Inflicts moderate fire damage upon random targets, the farther the targets are from Yor'sahj, the more damage they take.
- Black Globule Periodically spawns Forgotten Ones which fixate and attack random targets.
- Green Globule Deals nature damage to random targets and anyone within 4 yards of the player.
- Purple Globule Inflicts Deep Corruption on every player causing every fifth healing or absorption effect cast on a player to trigger a violent explosion dealing moderate Shadow damage to all players.
The important notion of this encounter isn't so much Yor'sahj himself as it is controlling which abilities he is capable of gaining. Aside from the oozes which spawn, Yor'sahj's innate ability of Void Bolt is relatively minor; you just tank swap in order to avoid it stacking too high, usually around three to four stacks. As for the oozes themselves, even though most people go by a complex priority system – which is the easiest way to explain the encounter in five seconds and works for LFR – it really isn't as bad as people think. Despite there seeming to be 20 possible ooze combinations that you could be faced with, it seems Blizzard was a little wiser than that and limited it to 6 possible combinations that you'll actually end up seeing.Handling the globules
| Colors || Kill || Dealing with it |
| Blue, Black, Yellow || Yellow || Group up, kill Void, kill adds |
| Green, Red, Black || Green || Group up, kill adds |
| Green, Red, Yellow || Green || Group up, heavy AOE healing, use CDs |
| Purple, Red, Black || Purple || Group up, kill adds |
| Purple, Green, Blue || Purple || Spread out, kill Void |
| Purple, Blue, Yellow || Purple || Group up, kill Void |
While that general rule of thumb generally works, there are a few iffy parts. For example, getting Purple, Yellow, Blue is the only time that you might actually consider allowing Purple to go through and instead kill off Yellow. Purple is only dangerous in situations where you cannot limit your healing, which is basically the AOE damage from any other ooze, however there is no raid damage with a Blue ooze, so the only healing that goes out is on the tanks. Through using tank cooldowns and a healer with slow, high healing spells, you can get through the entire phase with only one or two explosions overall, which doesn't put the raid in any danger. This is the only time that you can consider allowing Purple to go through. With any other color, either the tank damage is too high or there's raid damage.
You may also want to consider switching to taking out Blue instead of Yellow on the Blue, Black, Yellow combination, but this largely depends on your raid composition. Yellow would bring more raid damage to the table, but it isn't all that bad, the worse part of the pairing is that Yellow will cause a second wave of adds to spawn from Black. If your raid has high AOE damage, then Yellow Black is certainly viable and potentially less annoying; it isn't just healers that take a hit from Blue's mana drain, your DPS can get smacked around by it too.Using Yor'sahj as a learning tool
Another thing to keep in mind is utilizing Yor'sahj for practice. He's a relatively easy encounter in normal mode, but his hard mode mechanic is to spawn four oozes instead of only three. This means that you're going to end up with a lot more of the nasty combinations such as Red and Green together. If you're thinking of working on Yor'sahj hard mode, then consider going through a few attempts of normal getting used to the motions of these more tricky combinations.Cleaning up
Overall, the encounter follows the basic principle of just cycling through slimes and dealing with the consequences of which have to reach the boss. There isn't all that much to it. The only truly dangerous combinations that you should watch out for is Red and Yellow which is ridiculously high raid damage to the degree that you'll want to use any raid cooldowns that you have at that point. If you struggle with Red and Yellow, Red with Green is actually far less raid damage provided that people can learn to stand relatively close to the boss but remain 4 yards apart.
The other tricky one is Green with Blue. Green causes some moderate raid damage, nothing all that high, but healers will be excessively low on mana due to Blue which can make healing people relatively tricky. Blue plus any AOE damage is usually a bad mix, but it all depends on your raid make-up and how frequently you've gotten Blue. Healers and DPS usually have a trick or two to regenerate some of their mana back, but if you get Blue two or three times in a row, they can run out of options and sit OOM until that void dies; if you run heavy on mana-dependent ranged classes, that can make it double-y tricky.
Good luck and have fun!
Ready Check shares all the strategies and inside information you need to take your raiding to the next level. Be sure to look up our strategy guides to Cataclysm's 5-man instances, and for more healer-centric advice, visit Raid Rx.