We'll Never See That Again, Surely

Given the name of this achievement and the nature of throwing a lump of flesh into the open void, it would be a crime if they never make another meta where we have to catch the lump on some future void-themed boss. You can call it 'Never Say Never'.

As for the actual meta, when you drop down from Echo of Neltharion you land in a shallow pool of water. Hop out and clear all the trash up to Sarkareth, but don't hop down to his room. Go back to that pool and swim down until you reach the bottom, where you'll start getting stacks of a DoT. When you reach 10 stacks you'll get the [spell=410277] debuff which reduces your max health by 30%.

If you die, you lose the debuff so you must survive all of P1 with reduced health. This is a personal achievement so if someone dies you can continue and anyone who throws their lump will still get the achieve.

When P1 ends you'll get given stacks of Oblivion and at 10 stacks the intermission will start and you'll be brought down into the Emptiness Between Stars. You have roughly 20 seconds to collect all 3 of the white circles to bring yourself back up top. If you go to the edge of the platform while in this phase you'll get an extra action button that will let you throw the lump off the edge. Once you've thrown yours you can kill the boss.

While the intermission between P1 and P2 is the easiest time since everyone is forced to go down, you can re-enter the Emptiness Between Stars during P2 and P3 by getting to 10 stacks of Oblivion again by using the fight mechanics. If for some reason you missed the clear in the intermission, just go down again and throw it then.

If you need help with the metas feel free to add me to Btag (NA only) or Discord!
Btag - FrostyShot#1667
Discord - yarini

To get the lump of flesh, stay in the pool that you drop down into after Echo of Neltharion and let the stacks reach 10. During the fight simply stand on the edge of the platform and press the extra action button to throw it off while you're in the star realm. Extra action button doesn't appear until you're near the edge.

Patch 12.0.5 removed [spell=401215] and everyone marked this dead — but there's still a way. You need 2 alts in the same party (any class works), position them pre-fight, and the phase still triggers. No raid group, no exploits.
Full solo walkthrough for We'll Never See That Again, Surely if you want the setup: https://youtu.be/2kFszF8pJgU