ATM the difficulty of an instance is depending on how many mobs you have to fight at one time (zerg battle). So far I have not seen any mobs (only 1 boss fight so far, I am lvl 55) where 2 mobs is interconnected with each other. I mean that when 1 of a type of mobs is in the vicinity of another type, they get stronger, or a new ability, or starts to play different.
Why are there no mobs in the game that interact/react to each other? Why must difficulty more or less only depend on amont of mobs or mob health with the combo of heavy dps?
Lost where no man has been lost before!