I beat this guy on my Guardian using solider gear, a great sword, and no cc's. It took me awhile to figure out something that worked, but since I never took enough damage to die I had a lot of time. Basically I realized he does this jump stomp thing every time before he starts to drain your life. So once he jumped you need to dodge his attack and start running/rolling away as quick as possible. The further away you are the less he heals from you. Also if you have a sword leap skill like the great sword 3 skill make sure to untarget him and you can use that to help yourself get further away. Also be careful about buffing yourself. The buffs should be applied right after he uses his life steal skill otherwise if the buff is still up after he starts stealing your life he gets those buffs too. Overall I found this boss quite annoying as someone who has played lots of RPGs and MMORPGs. For a casual player I could see this being a hard fight. It is a little unforgiving compared to the other story mode boss fights. If I made one mistake he would gain a significant amount of health back. If I made several mistakes he would be at full life again. My suggestion is even though people are beating him it is a story mode boss, and while it doesn't need to be a cake walk this boss should be toned down a little either by increasing the cooldown of his life steal or change the percentage of life steal.