The twin val’kyrs have an interesting “light” and “dark” mechanic that sounds confusing at first, but is actually incredibly easy to pick up. Basically, if you can down faction champions, the twins will not offer any challenge whatsoever.
See, every member of the raid chooses to become light or dark. If you’re dark, you deal more damage to light targets, absorb all dark damage, but take a crap ton of damage from light energy. And, of course, vice versa.
Each twin pulses an aura that deals damage. The dark one hits everyone for 1500 shadow damage, the light one hits everyone for 1500 fire damage. If you have, say, the light buff, that aura that pulses fire damage every 2 seconds is simply absorbed.
As many of you are no doubt aware, arcane mages have this talent called Incanter’s Absorption. This talent increases your spellpower whenever you absorb damage.
I’ll let that sink in for a second.
Let’s say you’re like me, and have roughly 20k hitpoints raidbuffed. The extra spellpower from your IA buff is capped at 5% of your maximum hitpoints, which in this case would be 1000.
With an AoE hitting you, and getting completely absorbed by you, for 1500 every 2 seconds, this means your spellpower is being increased by 225 every 2 seconds. Effectively, you will hit the IA cap 10 seconds into the fight, and remain at that cap for the entire duration of the fight.
Let’s say you are like me, and your spellpower sits at something like 2700 fully raid buffed. That means you will have at least 3700 spellpower for the entire fight.
Yeah. Yeah I know. Yeah I’m kinda expecting it to get nerfed too.
Another little tidbit.
The Light AoE is, in fact, fire damage. You can use Fire Ward to absorb this damage, assuming you have the dark buff. This can get you to the IA cap even faster, and if you have Frost Warding, can provide some very effective mana regeneration.
However, note that because it costs a GCD, it’s best to only cast it when you are moving. The point is to increase your DPS, not decrease it.
And the final note!
As with everything, it’s not all totally awesome buffs all the way.
The second major feature of the twins fight are these colored orbs that float all over. Ones that match your color explode and grant you some serious buffage, ones that are the opposite color explode and melt and your face.
However, both explosions will interrupt channeled spells*. Yes, even the one you fully absorb, and thus take no damage from, will cause bad things to happen to your evocation and arcane missile spells.
You have been warned.
* Not “interrupt” interrupt, but cause pushback/knockback, or whatever you want to call it.