I've seen quite a few people try to get a dependable Metamorphosis tanking build and I personally loved to idea of being able to tank as a Warlock in pre-WoD expansions.
Mists of Pandaria offered the perfect ability to do this through a glyph.
My idea for this LRE would be to have it require knowing Metamorphosis.
Your regular Metamorphosis would be replaced by Demonic Apotheosis, a permanent stance rather than a temporary shapeshift. In this stance the special Metamorphosis abilities are useable and the damage increase from Metamorphosis is replaced by a 10% damage mitigation and slightly increased threat generation.
edit: considering MFB causes the tank to deal less damage a similar effect would probably make sense in this case
Demonic Apotheosis would limit you to fire and shadow spells and abilities and stuff that is useable in all other shapeshifts.
Since I am not very experienced with tanking I am gonna add some additional ideas to add to this RE or some seperate supporting REs in here. I'd appreciate some feedback on this.
Demonic Apotheosis would allow the user to use both Demon Armor and Fel Armor at the same time
The effects of Demon Armor and/or Fel Armor are doubled while Demonic Apotheosis is active
edit: double might be a bit much in hindsight
new idea: Demon Armor grants 50% additional armor, Fel Armor provides a percentage of spirit or intellect as resistances against all spell schools
The Immolation Aura, Hellfire, Shadowfury and Shadow Cleave can now apply the Soul Leech talent effect (the effect would be reduced for Immolation Aura and Hellfire)
edit: this probably should be more in line with the Ret Paladin Talent 'Vindication'
new idea: Immolation Aura and Hellfire now have a chance to apply the attack power reduction part of the Soul Leech talent and benefit from the Soul Leech Capstone effect, Shadow Cleave and Shadowfury benefit completely from the Talent, but only provide a third of the healing
Rain of Fire or Hellfire get a similar effect to Consecration (Emanate) from Emanating Light, in the case of Rain of Fire the ability would turn into a instant cast, granting you a minor stacking mitigation buff. In the case of Hellfire the spell would allow you to move while channeling, deal reduced damage to the caster
and or grant a 5-10% damage mitigation buff while channeling
edit: in both cases a reduction in outgoing damage would probably be a good idea
Searing Pain will now also hit other enemies affected by Immolate in a small radius
edit: as a standalone RE this should probably require MFB or Demonic Apotheosis to be active
Getting hit by attacks while channeling Hellfire has a chance to unleash additional, larger Hellfire Bursts which reduce the
movement and attackspeed of nearby enemies
edit: movement speed reduction would provide too much value, the attackspeed reduction would be in line with an undmodified Thunderclap
While casting shadow spells attacks made against the caster have a chance to cause a burst of shadow energy around the caster, leeching some health from enemies around the caster.
While casting fire spells a similar effect is active, instead resulting in a burst of fire, dealing some damage and reducing nearby enemies attack speed by 10%
Drain Life, Mana and Soul have a chance to send additional links towards attackers while channeling, applying a weaker effect to additional affected enemies.
- As an additional support for this tanking RE the 'Mind over Matter' RE could be changed to include Demonic Apotheosis
Feel free to reply with some other ideas, feedback of any kind would be appreciated.
edit: cleaned the post a bit up, added another support idea