The keys to keeping people alive on Archimonde:
1. Make sure everyone knows how to use their tears correctly. If there's a problem with this, they can always practice jumping off the cliff at the Night Elf camp.
2. Make sure you're decursing effectively. Have decursers spread evenly throughout the raid, and make sure they know what they're doing.
3. Handle doomfires effectively.
Number 3 is obviously the most important (and most difficult) part of this fight to master.
The first part of dealing with doomfires is that they follow people, some times for their full duration. If you have a doomfire chasing you, run STRAIGHT BACK away from the raid. Don't change directions or loop around until you're absolutely sure that the fire isn't following you around anymore. If you turn back too early you can surround people with fire... which is bad, as it makes the second part of dealing with doomfires much more difficult.
The second part of dealing with doomfires is knowing when fear is about to happen. Have DBM or BigWigs installed. They'll tell you when the fear cooldown is up. When the CD is up, you should be as far away from any doomfires as possible. If you're close enough to a doomfire when the CD is up to possibly get feared into it, you'd better make sure that your trinket/WotF cooldown is up. Remember, not dying is priority #1. DPS is priority #2. I've been through Archimonde fights where I haven't even needed to trinket because I always positioned myself intelligently for the fears. (Keep in mind that when positioning yourself for fear that you shouldn't move out of range of your decursers. Grip + no decurser = dead.
The final part of dealing with doomfire is simply paying attention to your surroundings. Zoom all the way out... ALL THE WAY. There's a keyboard command to set your max zoom range farther than the original settings. Use it. Knowing what's going on 20-30 yards around me in all directions has saved my life on more occasions than one.
If you just play smart and everyone focuses on survival, Archimonde will die eventually. Enjoy the sick loot table.
Sorry for the essay.
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Obnauticus/Warlock/Altar of Storms (main)
5/5 MH and 9/9 BT
Oldtuna/Paladin/Nordrassil (alt)
7/10 Kara 2/2 GL LOL