That spec is just a no-regen spec... nothing new. Plenty of us who raid as Enhance could take it for bosses, but we don't since we prefer more aoe-friendly builds.
Magma 3 times every 60s is 3342 mana.
FN every 6 seconds for 60s is 9040 mana. (your unbuffed mana pool is pretty much gone now)
CL every 6 seconds for 60s is 11420 mana.
If you can keep this up for your AoE with raidbuffs and SR then go ahead and ditch your regen. Or maybe just take the oom time for extra single target damage.