Bastion of Twilight: Valiona and Theralion

These twin bosses share an HP pool and share threat throughout the fight. The fight consists of 2 cycling phases. It begins with Valiona on the ground and Theralion in the air and every so often the dragons will switch. Enrage timer is 10minutes

Valiona Abilities:
Ground
Blackout: Debuff affecting random raid member. Absorbs 20000 healing. When removed or expires, all enemies in 8 yards share 250000 shadow damage.
Devouring flame: Boss faces a random member. 2.5 second cast. Then 25000 damage every second in cone infront of boss.

Flying
Deep Breath: Inflicts 15000 Shadow Damage and sends the target to the Twilight realm. This is a linear AOE attack like Onyxia's deep breath.
Twilight Meteor: Purple arrow appears on your head. When the metoer lands deals lots of damage shared between pary members, so stack up.

Theralion Abilities:
Ground:
Engulphing Magic: The Engulphing Magic Mirrors all damage and healing you do, inflicting shadow damage equal to the damage or healing you do to allies with 10 yards of you.
Fabulous Flames (or Dying breath): large flame puddle dealing 7500 damage per second.

Dazzling destruction: Vortexs applears on ground and a meteor effect lands on the, Inflicts 15000 shadow damage to all enemies in the vortex and sends them to the twilight realm.
Twilight Blast: 17,000 Shadow Damage to a random raid member and all nearby allies.

Tactics
Valiona on Ground:
Tank boss in middle (usual dragon hit zones)
Spread for Twlight blast, all stack to dispell Blackout safely. Entire raid needs to avoid the Dazzling Destructions.

Theralion on Ground:
Group for Twlight Meteor. Person with Engulphing magic needs to run away from raid before using any abilites. The Fabulous Flames AOE is big so best have one member marked so the others can follow when moving out of the puddle and trying to stay grouped.
When you see Deep Breath announced look up to see where Valiona is casting it, make sure you are not in her trajectory or you will die.