Eden Eternal/YMMV

• That One Attack: Unremovable damage-over-time attacks which stack and damage reflection buffs/debuffs. Made more annoying/challenging by the fact that most player interrupts all trigger the boss's Mercy Invincibility timer and the bosses can spam the attacks.
• They Changed It, Now It Sucks / Broken Base: The Bard skill "Burning Metal" had been changed in a patch in Aeria Games' version, given a 2-second cast time from previously being instant-cast. As this change effectively changed its kiting abilities as well as its use in normal parties, many people were unhappy with this change, while just as many were happy about it since then other people couldn't 'exploit' it for said kiting abilities.