This World is a Prism

Might sound obvious but can't be soloed at the moment.
You can only pick up one orb at a time.
Hence, you need a minimum of 4 toons.

A full guide for all achivments will be posted later by our raid team’s organiser “Amazingdruid”.

For this achievement you will want to collect the four Prismas around phase 2 of the Sylvannas encounter. There will be one Prisma for each covenant. These Prismas will spawn on fixed spots through the phase 2.
1 Prisma is right behind you where you spawn.
2nd Prisma is on the furthest back on the 3rd chain-platform
3rd Prisma is on the left end of the 4th chain-platform (and can be seen when you start in phase 2)
4th Prisma is on the 5th chain-platform in the far end (run strait and go to the left).
While the Prismas’ spawn location is fixed, the order of them is random. It is important to remember the order of how the Prisma spawn as this will trigger the final effect of the achievement in phase 3.
After collecting all 4 Prismas and entering Phase 3. All players will start on the “maldraxxus” platform which can be seen as there is a large Maldraxxus symbol on the platform. If you run clockwise the platforms are (when starting at the Maldraxxus platform):

Maldraxxus – Venture – Kyrian – Night Fae.
Through phase 3, Anduin is fighting Jaina, Bolvard and Thrall on the middle platform. During these fight Auduin will at times cast Blasphemy https://www.wowhead.com/spell=357731/blasphemy. By having each Prisma carrier standing on their platform (Maldraxxus Prism on the Maldraxxus symbol etc.) the focusing Prisma will be activated.

However, the players with the Prismas must enter the symbols in the same order as the orbs spawn, els they will interrupt each other.
So pick up the Prisma. Have each player jump over to the platform representing their Prisma and go on top off the symbols in the same order as the Prismas are found before Anduin finishes his cast on:

Update on this comment. You DO NOT need to do it in order anymore. Just all stand on the sigils and cast it at the same time. Did it today with my guild.