This has probably been posted before.
I see a couple of things wrong with debuffs cast by npc's in the game.
1) Mob waits til it is down to its last sliver of life then casts a dot or ransack which lasts up to two minutes (that I've encountered so far).
2) Mob dies. The ransack/dot cast by said mob hangs around still. I sit on my butt for two minutes waiting for ransack to go away because as an MA I can't heal while I've been ransacked. I'm sure other classes are affected too. My dmg output goes down and I can't heal. I sit or I die if I try to fight.
Solutions:
1) If the mob hasn't casted a debuff by the time it's 50% dead, then it shouldn't. That last second debuff is pissing me off quite a bit.
-OR-
2) Make the debuff last a lot less time. If I'm fighting multiple mobs, the others can proceed to debuff me to their hearts' content, but the original dead debuffer should have its debuff done away with or else not last as long.
Seems like a minor thing to me. I'm speaking strictly from a PvM perspective. Not sure what the implications would be for PvP.