After doing some experimentation with different builds on test dummies, I have concluded the following results:
Scepter as your first big item is garbage and late game is decent.
I set up the following Faceless Voids at first.
Void 1: Scepter, Agility Treads, Mask of Madness
Void 2: Mask of Madness, Battle Fury, Agility Treads
Void 3: Mask of Madness, Hand of Midas, Agility Treads
Void 4: Mask of Madness, Agility Treads, Maelstrom
Void 4 ended up having the highest raw damage output on a bot, with Void 2 not far behind him. Void 1 was in third place, with Void 3 in last.
Then I tried some various experimentation with two 6-slotted voids.
6-slotted Void 1: Scepter, Agility Treads, Mask of Madness, Butterfly, Mjollnir. Daedalus
6-slotted Void 2: Assault Cuirass, Agility Treads, Mask of Madness, Butterfly, Mjollnir, and Daedalus
Void #1 won in damage output in this round, by about 400. That late in the game, it turns out more Chronosphere time is better than having another item (unless it's a Rapier, which I did not try).
Edit: Yes, I am aware the Maelstrom/Mjollnir Chain Lightning procs are magic damage, however, that is something that occurs in game, so it's not really fair to throw it out. Actual results may vary obviously.