We had issues with this at first, then we came up with a decent tactic that seems to work for us.
After he lays down his large purple AOE, he will start with the jumping to people in the raid. We used two tanks and as soon as he jumped, the other tank would immediately taunt him back. This helped keep DPS alive to burn him down and it made it more predictable on who to heal.
You can check out our guide on him Warlord Kephess Guide and watch our video here