Not so long back, I played a game that had an interesting way of dealing with PvE combat and mix it up a little, making it more interesting. What they did was give each mob a random special attribute. For example, Some might be weak against fire, others might be again water, some might have extra hits than normal for that mob type, some might have extra armour or might move faster than usual.
This could be applied to the MOBs in EnB. I dont know how difficult a task that would be though, so that is why it is only a suggestion.