Bronjahm:

• Shadow Bolt: Fires a bolt of shadow energy at the target inflicting 2k - 4k shadow damage.
• Corrupt Soul: Channels a spell corrupt a portion of the targets soul causing 400 shadow damage per tick, after the channeling is complete a Corrupted Soul Fragment will spawn on the player (knocking them down) and slowly move toward Bronjahm healing him upon contact.
• Soul Storm: At 30% Bronjahm will teleport to the center of the room and cause a massive storm to swirl around the room causing 400 shadow damage per second along slowing movement by speed by 30%, this affects players 10 yards away from him and lasts 10 minutes.
• Fear: Causes the target to run in fear for 5 seconds, Bronjahm will cast this during the soulstorm.
• Magic's Bane:  Slash in a circular arc, inflicting 2500 Physical damage to each target plus an additional amount equal to half the target's total mana. Cannot
  exceed 10,000 total damage (15K heroic)
• Mark of Blood (heroic):  Place a Mark of Blood on an enemy.  Whenever the marked enemy deals damage to a target, that target is healed for 4% of its maximum health. Lasts for 20 sec

First trick is that he'll "drain soul" someone randomly.   Once the channel is complete, it creates a crystal that moves towards him and will heal him.    So, kite away, dps kill crystal.

Second trick is the soul storm, just get in melee range after he teleports.   He'll also randomly fear people during this, so that might screw then over making them run away and into soul storm, heal through that.

Another trick appears that he'll jack over anyone with high mana, so burn your pool a bit asap.  

In heroic only maybe, there's that debuff that makes you heal him.  Don't attack during that if you want the fight shorter.

Devourer of Souls:

• Phantom Blast:  15 yd range — Inflicts 11700 to 12300 Shadow damage. 2 sec cast. 17550-18450 on Heroic
• Mirrored Soul:  The Overseer of Souls mirrors the targets soul! A percentage of damage from the Overseer of Souls is being mirrored with you. 2 sec cast
• Well of Souls:  The Overseer of Souls leaps towards a target, slamming the ground creating a Well of Souls, which Inflicts 2925 to 3075 Shadow damage. Instant. 3900 to 4100 Shadow damage on heroic
• Unleashed Souls:  The Overseer of Souls is releasing tormented souls periodically. 0.85 sec cast. Lasts 5 seconds. (15 sec cooldown)
• Wailing Soul:  Lets loose Wailing Souls, inflicting 4875 to 5125 Shadow damage to anyone in front of her and knocking them back (90 degree sweep of room, ticks every 0.4 sec)

First trick is Mirror Soul, basically a debuff that causes you to reflect all damage you do back to you.   So, don't kill yourself.

Second trick appears to be void zones to not stand in.

Third trick appears to be the whole, C'Thun Eye Beams, Lurker Spout, Mimiron P3WP3W Laser Barrage, etc thing.  Only 90 degree sweep though from the targetted player, avoid it.

Forth trick is adds, Unleashed Souls will summon wraiths to easily kill off.

Trash:

Soulguard Watchman 

Bone giant. Always in groups of two. Casts Shroud of Runes:
eight-second/four-charge spell reflect. Also Unholy Rage: increases
damage/attack speed by 10% for 10 seconds.

Spiteful Apparition 

Floating skull. Invisible. Aggro radius of 15-20 yards. Once aggroed, it will close to melee then cast Spite once for 4500-5500 Shadow damage if it is not killed first. Then despawns.

Soulguard Adept

Cultist. Part of the four/five-pulls. Casts Shadow Bolt.
Also Shadow Mend: 2.5 sec cast 9k-11k heal and Drain Life: 6000 health over 4 sec

Soulguard Animator

Cultist. Part of the three/five-pulls.
Also Soul Sickness: 60% slow for 8 sec. and 5 second stun if not removed before it wears off

Soulguard Bonecaster

Skeletal mage. Part of the four/five-pulls. Casts Bone Volley: 3770-4230 damage to enemies within 30 yards. Also
Shield of Bones: Absorbs 5k damage, if 5k absorbed, deals 5k damage to
enemies within 15 yards

Soulguard Reaper

Death knight. Part of the four-pulls. Casts Shadow Lance: 4475-5525 Shadowfrost damage and Frost Nova.

Soul Horror

Shade. Part of the three/five-pulls. Being channeled by the two/four surrounding it.

Spectral Warden

Wraith. Solo pull. Three between Bronjahm and the reliquary. Veil of Shadow: 75% incoming heals reduction curse. Also: Wail of Souls: 4250-5750 Shadow to all inside 40 yards.