Whew, what a morning. Took out Mephisto in one go, then removed Izual as well. I seem to be much lower in restore potions. I had several full restores before Mephiso and none after.
As an assassin, my best strategy is a) use traps to clear the area of lesser but annoying enemies.
Then for the main dude the left and right clicks are for dragon claw and cobra strike. A couple of cobra strikes then a dragon claw to replenish life and mana.
Now where is the waypoint in the city of the damned? There are some tough opponents just inside the door.