Teron Gorefiend, one of my personal favorites from previous Warcraft games, quite a bit of lore behind this guy as well as a questline in shadowmoon valley related to his freedom from imprisonment of do-gooders and so on.  Sadly he now drops purples and therefore must die.

Abilities

4,100,000 HP

Melee – Hits for an average of 6,000 or so on plate

Incinerate – Randomly targeted spell used every 20 seconds, deals 2775 – 3225 fire damage as well as additional fire damage every second for 3 seconds.

Doom Blossom – Forms in dark clouds above the boss, fires random shadow bolts into the raid hitting for around 1500 damage.

Crushing Shadows – Randomly targeted debuff hitting up to 5 players, increases shadow damage taken by 50% for 15 seconds.

Shadow of Death – Randomly targeted ability used every 30 seconds, targeted player will die after 55 seconds have passed, turning into a ghost for a total of 60 seconds, cannot be placed on main target(tank.)

The Fight

The gorefiend fight, although possessing no alternate phases nor stages of the encounter, does pose quite a few complexities in terms of strategy due to its rather unique ghost mechanics, the result of his Shadow of Death ability.

10 Seconds into the fight the first player will be marked with ‘Shadow of Death,’ resulting in their unavoidable demise 55 seconds later.  Upon death 4 shadowy constructs will spawn, these must be annihilated by the now ghostly player quickly and efficiently lest any manage to run free and practically guarantee a wipe.

However before fully explaining the ghosts let’s return to the boss himself, he’ll hit quite hard, even on your main tank, therefore a critical hit or two can cause high damage spiking, although it’s simple to heal through.

The constantly forming doom blossoms will begin to pose more and more of a threat to the raid as the fight progresses, rapidly becoming far more than the initial annoyance they posed when only a single or perhaps two were firing shadowbolts.  The bosses shadow damage increasing debuff doesn’t help any either.

Randomly targeted incinerates will be quite the pain throughout the combat as well, dealing the initial damage plus around 3,000 or so per second, making it quite capable of killing a player when combined with the random shadowbolts.

Ghost Form

Once a player has received shadow of death they have exactly 55 seconds to live.  At this point they can choose to blow all cooldowns in an attempt to deal as much damage prior to death, however throwing a soulstone on the player will allow them to resurrect post ghost-status.

Regardless, once the debuff has been received you should leave a minimum of 15 seconds or so on the timer before running for the doorway, therefore leaving your corpse as far away from the raid as possible, this would be due to the shadowy constructs.

The main problem with constructs is that, aside from 3,000 or so melee damage and a stacking debuff per attack, they are immune to all attack aside from the ghost form players, making them impossible to stop by those still living.

As soon as you die you’ll gain the ghost control bar, a pet bar of sorts that handles your ghostly abilities as labeled below:

Spirite Strike – Deals 700 damage and decreases targets damage by 10% for 5 seconds, melee attack.

Spirit Lance – Deals 6,000 damage and decreases targets movement speed by 30%, stacks 3 times.

Spirit Volley – Deals 10,000 damage to all nearby enemies, 15 second cooldown/12 yard range.

Spirit Chains – Shackles all nearby enemies for 5 seconds, 15 second cooldown/12 yard range.

Spirit Shield – Absorbs up to 12,000 shadow damage on a friendly target, 90 second cooldown.

As soon as you become a ghost you’ll need to shackle the 4 spawned constructs, preventing them in any manner possible from rushing the raid and interfering in the continuing Gorefiend fight.  Use the AoE, spirit volley, as much as possible combined with both the shackles and spirit lance attack.

You should drop all constructs in somewhere around 40-50 seconds, giving you enough time to aid any other ghosts with renegade constructs should they exist or beat on Gorefiend with spirit strike, the boss is immune to all other attacks.