I have get some messsge from the ptr videos，and there are still several points I dont understand

First, there are some dark and light portals on the ground，when you click on it you
trans into dark or light form, which let you deal less damage to the same attribute boss and bonus damage to another one。

When the fight begins， there are many tiny dark and light orbs spawns and fluttering randomly, when any player touch it will burst and deal dmg to the player with different attribute, but the same attribute player wont hurt and will gain "Surge of Speed and 7-8 stacks of "Powering Up", when"Surge of Speed" stacks
to 100 they will increase their dmg output to the different attribute boss.

Sometimes one of the sisters will cast Dark or Light Vortex, players should found the portal and change their form to avoid the damage when they start casting, after casting they begin to channel the spell, harm the different attribute players, but the same attribute players will aslo get Surge of Speed and 4-5 stacks of "Powering Up" each tick such as the dark and light orbs, Trans bwtween dark and light form wont reset the stack of Powering Up.

The Valkyr can also heal themselves. One of them will put a shield and start to cast "Twin's Pact", you need 250000 dmg to break the shield and interrupt the healing within 15 seconds.

There are several ability I dont know how they works, they are:
Power of the Twins , Val'kyr Quickness and Twin Spike
Another question is how to arrange your dps, healing and raid debuff on the sisters.