Mor Grayhoof has several offensive abilities:
Hurricane: He'll cast it every now and again around himself, turning him away from the group doesn't seem to matter. He can't move while casting this though, so either back away or ignore it entirely if your group has good healers.
AE Moonfire: This is also done to everyone around Mor, so turning again doesn't matter. This is a magic effect and should be dispelled ASAP by a priest or paladin. Note that the range of this AE moonfire is 30 yards, and it can be outranged by healers/ranged DPS if Mor is tanked in the opposite corner of the room from them.
Animal forms: Eventually Mor will get mad and change into various animal forms. Just continue the fight as normal.
Mor's DEFENSIVE abilities are really what makes or breaks the fight. If you don't have the means to stop him from healing, you lose.
Healing Touch: Mor has a healing touch that heals him for 7000 health easily without critting. This is easy to spot and interrupt. Mor is IMMUNE to stun effects, so plan your interrupts accordingly.
Rejuvenate: This spell is the one that is most often overlooked, and is also the one which is most important to stop. Mor's Rejuvenate heals him for 1000 hp per tick. It is a magic effect and must be dispelled immediately or he will regain his health back too quickly to be killed.
Mor's FormsEdit
Caster: During this phase, which Mor periodically shifts between, is a Tauren druid in feralheart. He attacks with his staff doing manageable damage. Periodically he will cast an instant AoE moonfire that hits between 400 and 500, as well as a channeled Hurricane that also does between 400 and 500 per dmg cycle. In this form, Mor can cast Rejuvenation and Healing Touch on himself. This is the form Mor will return to between form shifts, to cast heals on himself and do AoE dmg to the group. Mor has an incredible amount of mana, so mana draining him is really not a viable option, and it takes him about 20 minutes to expend all his mana.
Bear: At about 75% hp, Mor will shift into bear form, gaining greatly increased armor, and typical bear abilities (slow and powerful attacks).
Cat: At about 50% hp, Mor shifts into cat form, gaining faster attacks, and a stacking debuff that reduces target armor by 75%. Unsure if this debuff is additive or multiplicative, however, healers need to be on their toes to overheal if the debuff starts stacking.
Sprite Darter: At about 25% hp, Mor will shift into this form. He will sometimes randomly and instantly sleep a member of the party(2 healers can be good for this phase). He also has a melee attack and an AoE arcane explosion type attack. Mor hasn't been observed to ever shift out of this form, and can be easily dpsed down. Spellcasters should be aware during this form Mor will have a periodic ability called "Reflection" which will reflect all offensive spells back at their caster. It looks like bright blue sparkles around him, and will fade after about 10 seconds.