While using Metamorphosis, your Hellfire spell no longer deals damage to you and does not need to be channeled.
Immolation Aura is a passive warlock ability learned at level 62 for those with the Demonology specialization. While under the effects of [Metamorphosis], [Hellfire] no longer deals damage to the warlock and is no longer channeled.
Patch 5.0.4 (28-August-2012): Changed from Ignites the area surrounds you, causing X Fire damage to all nearby enemies every 1 sec. Lasts 15 sec.
Patch 4.0.6 (8-Feb-2011): Immolation Aura damage has been reduced by roughly 30%.