I'm posting this on behalf of a friend.

on 25h November 2017 the following update in the patch notes happened:

PVP
* Global healing and damage values have been drastically reduced. Time to live should be much longer now.

That resulted with a nerf around 75% to healing and damage. However there is an ability for Defilers (clerics) that is called Aggressive Avarice that did not get nerfed healing wise. Basically it's an ability that you can spend a legendary Point on to make it heal you for 6% of your total healing per Greed stack (max 5 stacks).

Every pvper who joins has at the very least +200k hp, meaning you can heal yourself for 60k easily. Building those greed stacks are also relatively easy so that means you can heal ridicoulusly with no effect of other peoples dps.

Conclusion: There may be other unreported abilities that didn't get affected by the pvp nerf, however this is one of them and its a game breaker.