My first instinctive approach to improving pvp would be:

- reduce all dmg done 50%
- reduce all healing 50%
- put sprint on 30sec cd, lasting 10 sec, doesn't end in combat
- change stun/polymorph cc into debuffs:
victims have 30% reduced movement speed/healing power
- snares reduce movement speed by 20%
- reduce general baseline movement speed by 20%, no more silly iceskate zooming in and out.

That would be a good start, now players could fight more and enjoy combat, work their dmg and heals, no burst kills, more control.

Next thing, change purify to "heroism" with a 1-3min cd lasting 4-10 sec and giving immunity to all cc no matter what.
The bubble should be renamed to a passive skill "adrenaline" that can proc only if you are hit by (fighting vs) 3 or more,
1min internal cd, reduces all dmg taken 20-30% for 5-10 sec depending on how many are fighting you, "the more, the more".
Balances out most 5v1 ganging up on people situations.

Something in that general direction would make everything way more playable.
And most importantly: update/upgrade the servers, tickrate, and change it to predictive mode
so skills pop off when they need to, and not like they do now, 2-3 seconds late, as if you had 500 ping.