There really isn't a whole lot to it. Max apocalypse and its synergies, 1 point in hex siphon, 10 points in demonic mastery, consume a tainted, and run defilers. Get as much -enemy fire resist/+damage as you can, so mang song's, 3/20 circlet with +15/-15, diabolos book, magefist, arach, opalvein, wraithsteps, -10 sunder, chaos gcs. Have your merc run infinity for extra fire pierce, and you're good.