Once you defeat him in chess, he comes out to fight you. He has a knockback and knock up. Corrival will pick one person in your raid and will spawn a X2 duplicate of that person that may kill them. This mob needs to be offtanked. If it is killed, he will exponentially repeating the killing/add summoning. Corrival splits roughly every 25% and when he does you must target the split that does not have buff with a green background and red heart and kill it. Once it is dead, he reforms as himself (which acts like a memblur) and you rinse and repeat.
--More information is needed--
also some time there are 3 dark heart but their are only one with the red buff so u have to look for the one with the red buff
Dark Hearted
Which name are you going to go after? Light or Dark?
They apparently changed it recently so that his splits are named "A Dark Hearted Corrival" and "A Light Hearted Corrival" to make it even easier to see which to kill. Just like before, you want to kill the dark hearted one, just now they are named so you don't have to look at the buff window on them.
We usually just tank corrival right where he's standing with a pally MT and Zerker OT. I put 3 healers in the MT group to help with some of the damage. When the adds spawn we just leave them where they are (too much moving around to pull them away). We have all DPS use a Mage MA for the add, since the adds sometimes wipe your target if you are within melee range. Basically thats it for the named just heal through whatever. When he forms back together, all DPS stops to allow one of the two tanks to grab the named back and pull it back in front of the throne.
The x2 is tanked by our moderately geared Bruiser with 1 healer, sometimes that healer is dedicated to him or is healing their group and him (usually fury or inquisitor). As long as everyone stays away from the x2 (max range) it's not that bad the x2 has an aoe that will damage or wipe a non tank if they are too close. The only time we have ran into issues on the x2 is when the named decides to memblur onto the x2 tank, usually that results in the OT grabbing the x2 until the bruiser is up again.