A common trend in PvP is filling your utilities with damage immunity skills and run around with glassy armor.
Now, this is not an issue for most classes but the worst offender is Engineers.
Delaying time so they can bring up their powerful turret heal while still keeping insane damage with their grenades (nerf please)
Mesmers distortion is in a good place, Endure Pain, Berserkers Stance and Shield Stance is not.
Instead of nerfing the turret healing or engineers defenses, just change most abilities across all professions that give unconditional invincibility or certain damage immunity.