As you know the main aim of achievement is to make nefarian 50% until air phase ends
so:
1) you need 3 shamans with hit cap
2) nef must be <70% until air phase starts
3) on air phase bl is casted and everybody hit nef (don' touch adds - shaman must interrupt all casts)
4) when phase ends we had nearly 45% of nef total hp and 3 mobs alive
5) then everybody jump on the ground (anyone who will be on columns will die)
6) adds on columns during 3rd phase shouldn't be tanked - only 3 shamans while standing on the ground interrupt mobs casts (only shaman because they have range interraption of casts Wind Shear - Spell - World of Warcraft