metamorphosis

[Fozzles]

from wowwikki:

Metamorphosis

Metamorphosis is a new 51-point talent in the Demonology tree of Warlocks.

The Demon Form abilities are the following:

* Challenging Howl (Instant, 15 sec cooldown): Taunts all enemies within 10 yards for 6 sec.
* Demon Charge (Instant, 45 sec cooldown): Charge an enemy, stunning it for 3 sec.
* Immolation Aura (Instant, 30 sec cooldown): Ignites the area surrounds you, causing 451 Fire damage to all nearby enemies every 1 sec. Lasts 15 sec.
* Shadow Cleave (Next melee, 6 sec cooldown): Inflicts 110 Shadow damage to an enemy target and nearby allies, affecting up to 3 targets.

When you learn this talent all demonic spells are learnt automatically and added to the Demonology tree of the spellbook. It's shapeshifting, like shadowform, and can't be dispelled.

While shapeshifted, the demon-form warlock is able to be banished. Demon-form is also susceptible to Exorcism (very dangerous since it can be glyphed to add silence) and Turn Evil but is immune to enslave demon.

Metamorphosis can be used for AoE Farming by picking up a bunch of Mobs an then using Immolation Aura and Shadow Cleave.

In PvP, it's only advisable when fighting in an one-on-one situation (primarily against Rogues), as in a brawl, a big, black and horned demon is the favourite target for everyone.

Of course, Metamorphosis can also be used as a flat damage boost for 30 seconds.

An interesting fact you should notice about this is it reduces your chance to be critically hit by 6%, this is just above what you need to be uncritable by a raid boss. Coupled with the armor increase and taunt it makes this a viable option for lock tanking. However there are currently no 80 range raid bosses that specifically require lock tanking.

[Jay-Ston]

Although this looks cool, I feel its a waste of time taking this spell, it gives no real benefit and offtanking can be done just as well with your FG coupled with the fact there are no benefits in the end game for this spell means your just getting style over content in my humble opinion.
Demonology is still as cool without it, most locks seem to like the FG/Emberstorm build to cover solo and pvp even with not so hot gear this is a solid option.