Bad Manner(oth)

I soloed this achievement after a bunch of attempts in Battle for Azeroth, and I thought I'd make a quick rundown with some accurate information and tips. Some of the information posted is a bit inaccurate and I thought I'd clear it up.

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• First off, this achievement can be tracked by using "Shift + Click" on it within the Achievement interface (thereafter it will show on the right). The text on the achievement will remain red until the requirement has been met midfight (i.e. the [npc=91241] has been killed with [spell=182336]). After the text turns white, indicating that requirements are met, you can safely kill the boss to get the achievement.
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• Soloing this at level 120, there are no abilities that can kill you other than the knockbacks that knock you off the edge! For this reason it's worthwhile to know a little bit about the fight. If you know the fight already, you can skip down to "Tips".
  
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  • The caveat to this is [spell=181099] ability which will instantly kill you if you avoid taking any damage before it expires! Once again, while soloing this, you are always taking some light damage so it's not a problem, but if you bring a friend (or friends) make sure they are taking some damage (the one time it's important to stand in bad stuff).
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Details of the fight:

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• Phase 1 of the fight is where there are 3 channeling Fel Iron Summoners with different abilities. The important summoner is the one standing in front of the Red Spire - it will cast [spell=181275]. This curse, when dispelled or naturally expiring, will spawn the [npc=91241] add that needs to be killed by [spell=182336] for the achievement.
  
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  • You need to kill the other Fel Iron Summoners and wait to kill the one in front of the Red Spire until the [spell=181275] has been cast; after you have that debuff, you can safely kill the summoner.
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• Phase 2 starts when all 3 Fel Iron Summoners are dead. This is what spawns Mannoroth himself.
  
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• Phase 3 is starts when Mannoroth gets to 65% health, and continues until he hits 35% health.
  
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  • Before Phase 4 of the fight, Mannoroth will cast a few abilities that knock you back:
    
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    • [spell=181359], which just knocks you back quite far.
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    • [spell=181597], which fears you away from Mannoroth.
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    • [spell=181735], which are green circles on the ground that get progressively bigger and knock you back if you stand in them.
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    • [spell=181799] (only in Phase 3), that channels a purple line from Mannoroth to you, pushing you away from him towards the edge of the platform. This ability gets progressively stronger in effect the longer it is channeled.
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    • Before Phase 4, all of the above abilities can be largely ignored if you stand in front of the Purple Spire. You will simply get pushed into the pillar and avoid getting knocked off.
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• Phase 4 starts at 35% health and lower, and this is the phase which you want to get the boss to in order to trigger the all-important [spell=182336] ability.
  
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  • Note that prior to Phase 4, the boss will cast [spell=181735] which is NOT what you need for the achievement. Only in Phase 4 does this ability become empowered.
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  • In Phase 4, ALL of the pillars have been destroyed, so you can no longer use them to prevent falling off the edge. You need to watch your positioning carefully to ensure this doesn't happen.
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  • It will take some time in Phase 4 for the boss to cast [spell=182336], and you need to deal with the boss abilities before that happens.
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  • The boss abilities in this phase are all simply empowered versions of his previous abilities. In my experience, the boss cast these in roughly the following order: [spell=181948] > [spell=185847] > [spell=185826] > [spell=185847] > [spell=182006] > [spell=182084] > [spell=185847] > [spell=185826] > [spell=185847] > [spell=182336]
    The important abilities to deal with are listed below:
    
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    • [spell=185826] knocks you back quite far like the regular version, but also spawns 3 waves (center, left and right) that move outwards from the boss. You need to ensure you are close to one edge of the platform with the boss facing the center so you are knocked towards the center, AND you need to avoid the waves after you land so you don't get knocked back a second time!
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    • [spell=182006] fears you for a few seconds towards the edge of the platform. As long as you are not too close to the edge, you shouldn't fall off from this. Note that once this expires you drop a pool of [spell=182031] on the ground, which slows movement and can be useful for [spell=182084].
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    • [spell=182084] works the exact same way as the regular version, with a purple line that the bosses channels to you - it pushes you away from the boss and builds in intensity as the channel continues. You want to make sure you start close to the boss at one side of the platform for this, as it will likely push you almost all the way across by the time it is done. As mentioned above, being pushed into a [spell=182084] pool will slow you down and help keep you from being pushed off.
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    • [spell=182336] is the ability you need to kite the [npc=91241] into so it gets hit. It starts as a small green circle on the ground, followed by a medium green circle, followed by a large green circle. This ability also knocks you back a bit, so make sure you are not too close to the edge when this happens!
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Tips

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• If your class/race has any movement abilities, these can help you in a pinch with the various knockback mechanics. These may include (but are not limited to) Rocket Jump, Disengage, [spell=195072], Blink, [spell=6544], etc. If they have a longer cooldown, it's worthwhile saving them for a particularly troublesome mechanic.
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• [spell=45438] as a Mage will root you in place during [spell=182084].
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• Speed increases help during [spell=182084] (e.g. Sprint, Dash, Nitro Boosts, Divine Steed, etc.) while you are running towards the boss against the push.
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• [spell=182084] pools on the ground (dropped after the [spell=182006] fear ability) slow your movement speed and can be helpful to prevent you from being pushed too far by [spell=182084].
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• I didn't have to damage the [npc=91241] at all prior to it being killed by [spell=182336]. Note that this ability does raid wide damage (even if not in the circle) so if the add gets hit by at least one circle, the other two should finish him off from splash damage (which is greater the closer you are to the circle on the ground). If you are having trouble with it not dying, you may need to carefully whittle it down with weak abilities (e.g. meleeing as a caster) to get it low enough. This can be very tricky at 120 given how much damage you do.
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• It is advised you dismiss all pets to avoid accidental damage to Mannoroth and the add.
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• You should remove your [item=158075] to avoid inadvertent splash damage and procs.
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• Check your trinkets, Corrupted gear and talents for anything that would deal uncontrolled damage and remove them. [spell=318280], [spell=318489] and [spell=318481] are some example of offenders.
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• As noted above, positioning is very important! If you are having trouble, you may need to practice positioning prior to each boss ability to make sure you remain on the platform after knockbacks/pushbacks.
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• I found Heroic difficulty was what worked for me, as the boss and adds had more health to fine tune damage to them. Remember that you need Mannoroth below 35% health to get him to do the [spell=182336] ability.
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• If doing this on Mythic Difficulty, there are some slight differences:
  
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  • Phase 1 is "skipped", make this in essence a 3-stage fight. The phases are still numbered 1-4, but in Phase 1 Gul'dan instantly kills all of the Fel Iron Summoners.
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  • In Mythic difficulty, [spell=181275] will automatically be applied to you during Phase 2 or Phase 3. For this reason, you need to wait until it is cast on to you before bringing the boss below 35%.
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  • Note that if you slowly DPS the boss to 35%, it's possible to have multiple [spell=181275] debuffs applied to you, and multiple [npc=91241]s spawn. This can potentially be useful to give you a greater chance to succeed at the achievement. Only one [npc=91241] needs to die from [spell=182336] to get you the achievement.
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1. Leave the summoner at the red crystal alone until one person gets the debuff from curse of legion. When curse of Legion is dispelled or goes away, a Doom Guard spawns. Then kill the summoner.
2. Have one tank take the doom guard away from everything else and take it down to about 5% hp.
3. Have another tank on Mannoroc and burn him down to 35%.
4. During P3 Mannoroc uses Empowered Fel Seeker (green waves). Have tank with doom guard chill by Mannoroc until its killed from this ability.

Easy peasy in Legion. You don't really need two tanks for this, but it simplifies it further.

HOW TO DO THIS ACHIEVEMENT THE EASY WAY:

Take off all your armor and weapon(s) so you don't kill the Doom Lord outright.

Stand in the sweet spot of the purple pillar. This will protect you from all knockbacks. Your whole fight/achievement will take place standing in the sweet spot at purple pillar.

Punch the Doom Lord down to about 30% health when he spawns.

Punch Mannoroth down to 30% to get him to last phase.

Keep standing in the sweet spot at purple pillar. Wait for Mannoroth to kill the Doom Lord with Empowered Felseeker.

When achievement goes from red text to white text, the criteria has been met and finish Mannoroth.

Congratulations.

https://www.youtube.com/watch?v=vV3VPzHIq2M