Monster Elite & Magic Affixes
I'd like to propose the idea of elite monsters and monster magic affixes. For example, let's say in a considerably big enough group of huntsmen:
There would be a reasonable chance for an elite huntsman to show up. This elite huntsman may come with 1.1 to 1.5 times more HP, and 1.1 to 1.3 times more EXP. While having all these bonuses, it also has more strength to it, and it's experience level is also slightly higher. Now elite monsters may be more common in other groups of monsters, like zombies or orcs, and less common in weaker monsters, like maggots. To distinguish an elite from a normal monster there could be a color variation, perhaps a gold layer or silver layer over the monster.
Now for magic affixes, think "Skeleton of Frost"; now this skeleton while probably having a blue color variation, it would also have ice resistance, and ice power. Ice power could be either attributed to the normal damage, or make a second attack consisting of ice damage. But the magic affix will only do what the name says, it won't make it have anymore HP unless it has an affix for that, but it should definitely give more EXP as it's more challenging than a normal skeleton.
This gives variation to PvM, so you don't always have to spend hours on end killing the same monster without any change to it or any mini-bosses you can fight to demonstrate your strength. Suggestions are welcome.
Thanks for reading (: