Even though some of your cards interact with opponents' graveyards, Leyline of the Void might be a good way to shut down grave power/Zombie decks.

Hinder, Spell Crumple, Altar of the Brood, Mesmeric Orb, and any eldrazi That shuffles your graveyard

Mesmeric Orb is super wonderful but will generate group hate against you so be careful with it - I personally chose not to run it and instead go for the option of being able to pick at opponents selectively instead of just broadly mill everybody constantly.
I've seen Altar of the Brood go right off in multiplayer in conjunction with Undead Alchemist. It's a bit more of a subtle effect and you don't risk murderising yourself in the process so it's a safer bet.

If you run Leyline of the Void I would also add Oblivion Sower it has a big butt to mill with your commander and could generate insane mana ramp for you.

love the deck. I love playing mill and this deck would be a great base for my mill deck i want to build

Is Traumatize too cute? I see you're considering Paradox Engine and that seems super sweet as well.

How do you feel about Memory Plunder?

If you have leyline of the void use helm of obedience it is an ifinite mill combo. Be careful when you use it because it will draw lots of hate.

Also laboratory maniac if you want to kill yourself to victory.

Fraying Sanity would essentially double any milling that you do.

Fun Fact: 'Pemmin's Aura' anagrams to 'I am superman'.