So plagued bosses spawn in some boss area’s in the game.
However their AI goes idle when your standing on raised surfaces, making it a realy cheesy way to kill bosses.
I would love for these to be fixed, to not make the game not to easy.
Below I will give some examples, but there are more of these.
The Shallows
In shallows overworld they usually spawn around here, and when you move to this position on the hill here the boss goes completly idle and just sits there.
This seems like a pathing issue, since there is space enough for him to come up here.
In shallows they can also spawn in brine vault, which has many places above where you can just kill the boss while it stands there being idle. In this case I would like to see the boss react and just give him a jump ability to jump up to the higher locations.
Mariner’s Keep
Here the boss also spawn in a location with lots of high places, making the boss idle while you attack. Please just give these bosses jump abilities like some other mobs have in the game. I would love to see this boss come towards me and just jump up onto the wall to kill me.
Nameless Pass
In this arena you can jump on the stone battering ram during the fight, this also makes the boss idle, perhaps moving a bit left/right.
Here another option would be during boss fights to block these locations off with temporary rubble. Like when there is a bounty in the war room the stairs on the right is suddenly blocked off.
When a boss spawns in the cerim chamber boss room, you can just walk to the stairs and go up to this location, this also turns the boss into idle. Here you could also block off the stairs to this place with ruble, when a plague boss spawns here. (just took screenshot without a boss to show the location)
Another way to fix some of these locations is to reuse the story boss barriers that prevents you from leaving a certain area.
But for overworld shallows location this might look a bit strange since its so open.
I really hope to expierence a real fear for these bosses when 1.0 comes out. Right now they seem to be stuck to a place with a invisible chain. When they go to far from the place they spawn they tend to stop and return there. This can be used to pull damage boss returns pull again over and over untill the boss dies while he just walks back and forth.
Just make the bosses to be able to chase you all over the zone, Give them ability to jump onto places. 
But then the only places left to hide would be small narrow places.