Byzola is the Boss mob of Shard of Hate and she is a pain. First there are three types of adds that come periodically during the fight.
A set of 3 heroic Nightblood Warriors
One Epic x 2 Nightblood
Class Specific Adds that must be killed by the corresponding classes in your raid.
The class adds are as follows:
Priest - Manifestation of Unholy
Mage - Manifestation of Arcane
Fighter - Manifestation of Physical
Scout - Manifestation of Shadowy
With that out of the way its time to talk about the encounter. Pulling Byzola seems to be done best by pulling him right where he spawns and tanking him in the little divet where its standing. The class adds, Arcane and Physical will spawn to the east and west down the paths. The class adds, Unholy and Shadowy will spawn just under the ledge of where Byzola is standing. Sometimes the class adds will not aggro the raid right away you must have two people assigned to target and pull any of the class adds right away. Now, the class adds if they spawn can only be damaged by the proper class. Mage for Mage, Fighter for Fighter..ect.
There is a 1/3 chance of getting class adds. Usually the Mage,Fighter,Scout adds drop rather fast but its the Priest add that usually causes havoc with a raid. Class adds will always spawn in pairs. First you will always get the Arcane and Physical. The second time if they spawn they will be the Unholy and Shadowy. That cycle will repeat if they should spawn again.
What makes these class adds so difficult is that the combination of both Hateful Intercession and Malaise, plus healers having to DPS and heal and cure is usually not very easy for most raids. Baleful Malaise causes you to be unable to target anything. This is where the beauty of Cure Potions come in handy. You will need plenty of Arcane Cure Potions for the Baleful Malaise effect as you can use a Cure Potion on yourself without having to target anything. If you attempt to cast anything or use an ability while Malaise is on you you will nuke yourself. When you have both Hateful Intercession and Malaise on you, you can not do anything at all. The Intercession effect will stifle anything you attempt to cast, so you must wait for it to expire or it get cured off you. There is no definite time on the spawn of the adds, but it doesnt seem to be any sooner than 25 seconds. Class adds are when you should be paying attention for Baleful Malaise and Hateful Intercession. The adds every 30 seconds will cast a large AOE (need name) on the raid. If more than one class is still up this will spell many problems for most raids. Try having healers come with a slight DPS setup for this encounter. Mystics, Furies and Wardens will probably been your highest DPS'ers on the healer add.
There is also a Curse called 'The Reviled' which is a effect placed on a member of the raid at all times. This effect is much like Trakanon's Hourglass effect. Only this effect will nuke you for roughly 70% of your health and power no matter what when it goes off. Anytime a person has The reviled they must move away from your raid approx 35 meters (see the abilities description as to why). You must not cure this effect. If this effect is cured it will trigger on the raid. You must move away. The icon looks like a Ogre Head with stars around his head. If you dont want to die to this, make sure you have atleast 75% of your life when it goes off. To ensure healers are not gone too long from this fight you can have your healers run away immediately and cure the curse on them and they can come back right away to the fight.
There is another Curse during this fight that will knock you up and backwards very hard with a moderate nuke as well. This icon looks like a upside down crown. When you get this effect just stop attacking, it only lasts for about 5 seconds on you.
The fight is rather simple if you think about it. Adds pop, kill adds. AOE's get cured and you win the fight. Only thing is there is alot going on and it will take practice and some good dps from everyone in your raid. Byzola herself doesnt hit very hard. Like Trakanon the encounter is made to make you hesitate and mess up yourselves. For this encounter you need to be perfect in all aspects or a little lucky with class adds. If class adds never spawn you have a good chance at winning.
If your guild is down to farming Trakanon rather easily and killing Maestro with ease, the combination of the Curse effects and the Curing of the AOE's will prove a fine challenge. But if you do not farm Trakanon or Maestro easily then Byzola might be a little beyond your guild at this time.
Good luck, Byzola can be harder than some Avatar encounters.