Grand Magus Telestra

1. Not a hard boss at all, watch out for her Ice Nova. You really can't avoid it so just heal through it, use and casting increase abilities. Mind-numbing Poison, Curse of Tongues work on her, Slow probably does as well.
2. She uses Gravity Well which pulls all players into the middle of the room, nothing special and does little damage.
3. At 50% she splits into 3, Fire, Arcane, and Frost. These can be crowd controlled, and you have a choice on who to kill first. The Arcane one does Time Stop which stuns everyone for 2 seconds, it gets annoying. Frost does and AoE Blizzard which is a 40 yard radius, so it definitely does the most damage to the party.
4. One all of the mages are dead you will continue the fight and finish her off.

Anomalus

1. The hardest part of this fight is Anomalus Create Rift ability. You have to switch to these and kill them down fast. They also spawn Crazed Mana Wraiths, which will also need to be killed.
2. Every 25% health he will summons an additional rift and charge it. This makes a shield around him, making him immune to damage for 45 seconds. If you kill down this rift and another one is open then you will be fighting the boss and rift. If you know which one is not charged kill it first, then kill the Charge Rift and it will be just you and Anomalus.

Ormorok the Tree-Shaper

1. This fight is a tank and spank, just watch out for the Crystal Spikes. They start of small, grow then spike up. Do not get caught in these, they will often kill you and are easy to avoid.
2. Casters he will pop Spell Reflect, this one has 4 charges. Use your weakest spells here so it doesn't hurt you too much.
3. On heroic little flowers will be spawned, these will root you. Making it hard to avoid the Crystal Spikes, so just DPS them down fast and continue beating on Ormorok.

Keristrasza

1. Melee needs to stand at her sides to avoid being knocked back by her tail sweep.
2. Intense Cold is a debuff aura she has, during the fight you need to keep moving even a little tap in any direction will cancel the aura. Jumping will also cancel it, but just move. You have to or it will keep stacking and eventually kill you.
3. Crystal Chains is a frost novaish ability and can be dispelled, during this time the intense cold aura is still stacking so if it can be removed then do it.