I've gone with the triple shot arcane missile lmb and the orb bombers with reduced mana cost for my rmb. For my 1 and 2 talents, I'm using freeze and knockback/stuns for zerg survivability. 3 is my familiar which I use the fire familiar that boosts DPS. My 4 is the archon, which is a GREAT talent for blue or gold mobs, or a zerg assault. Among my passive talents is the 2 second slow for any mob hit with an arcane spell, so the triple missile has that affect. My normal tactics on hard fights are to back into a portal so everything has to come through a funnel. Then I machine-gun the portal, and freeze or knock it back if it gets too thick. My companion is the Templar which I've stam-stacked. He has about 14,000 health and 1500 armor right now, Act 2 Nightmare at level 45, and he pretty much never dies. He's a very good tank. He has the taunt and intercept talents. He crowds up doorways for me, it's kind of funny to see. I can't tell you how many bosses I've killed with him just jamming up a funnel and me nuking from behind him. He stands in fire, in puddles, doesn't seem to bother him too much.