The NexusUpon entering the instance, take the left path, there is a single pat here, kill and continue down the ramp to the left. there is a pat mob here and then there is some mobs frozen the break free as soon as you come close. the 3rd iced mob is boss(in Heroic, not sure if he's there in normal).
First Boss: Commander KolurgWhen pulling this boss, the tank should pull him right back to the start of the ramp, as one of his abilities is a fear, which can send you running into other mobs if not pulled back far enough. He has 2 adds with him, who should be taken down first, then the boss. Dps should step out when he does his whirlwind. he has a charge, which is not that damaging, but if you are unsure, then stack up, and run out when when that whirlwind comes.
Second Boss: Grand Magus Telestra2 stages to this fight, first stage is just Tank and Spank. At 66% and 33% she splits into 3, and all 3 have to be killed before she will reform and do it all again. the usual kill order for the split is Purple, Blue then Red. Purple, stuns and polly morphs, blue has blizzard AoE and arcane just does single target damage. this fight can be hard for healers and from what i have heard near impossible to tank all the adds.
Third Boss: AnomalusAt multiple times during this encounter The boss will create rifts, these should be taken down straight away, and in some cases he becomes immune until the rift is destroyed. So a fairly simple fight, just attack adds and then back to boss.
Forth Boss: Ormorok the Tree-Shaperthere are some small lashers in the area before this boss, as well as mobs,. the lashers do not die until Ormorok is dead, so you have to keep moving in this area.
When you get to Ormorok, everyone should stack on him and should be just tanked in the middle where he stands. This is to avoid the crystal spikes that he cast's after 3 seconds. aprt from staying in nice and close this is a simple fight.
Fifth Boss: KeristraszaThere is a pat in the room once he is killed, this fight is started by unlocking the 3 crystal balls around the room. Once this is done, there is a De-Buff "intense cold" that should be kept to a minimum. This is done by simply moving. Either slight left to right, or a jump does it also. This limits casters a lot to instant cast mostly. She will also cast "icechain" which hold you in place, use what you can to break out of this, if you can, otherwise the healer should just heal thru it. and dps should stand to her side, rather then behind her, as her tail can sweep and knock you and do a fair amount of damage.
Enjoy