Just some ideas, maybe for the future.
Dynamic resolution scale (aka automatic resolution) - This is a new ascending thing on games and helps a lot (A LOT!) low-end and medium-range PCs. And even some high-end PCs. It makes sure you have a steady FPS on every area and with a lot of monsters around.
Deferred rendering - A lot of games are adding this and makes some games more smooth and with amazing lighting.
Heavy DoT based class (maybe Warlock?)