Q u o t e: Atma's Amulet is the item needed. It's worth the drop in AR, because in hell the Amp proc will AT THE VERY LEAST double your killing speed. It is the single best item for physical damage-based builds in the game.
The proc % really makes me question this statement. I personally prefer higher procing decrep or elemental damage for phys immunes. If they are not phys immune, then doubling is more of an overstatement...the only nonphys immune where I fell it can matter is on Baal...but again the proc % is so low you can kill him with out it even going off at times.
Not saying atma's is crap, just not sure I agree with it being quite so important in general...some builds, yes, it is damn near indispensable.
Calmguy: There is good reason why you aren't using Heaven's. the range is total crap. You wiff a lot with it. Grief is the superior weapon in most cases. Baranar's is a damn spiffy, cheap weapon which can be used even in uber tristram with good effect. Seeing as how you are going down the runeword track, I will likely leave most other suggestions alone.
"The only difference between genius and stupidity is that genius has its limits" Einstein