Weird Encounter With Warlock Healer

abanindra

So I was doing vos the other day and we had a warlock healer. I have not played warlock class so dont have much idea about it hence the post. He was spamming some kind of skill on me and rest of th team which was proccing 0 dmg constantly on my toon and his dmg on the board was increasing by that (even when we were out of combat). He had almost similar dmg on the board as th 2nd (boa tr) top dps. never saw something like that so I was curious what was he doing? or is it some legacy toon stuff?