Hey - Mike's friend here - here are my thoughts:
With an averange CMC of 4.4 I would consider adding an 11th ramp spell (if I counted right). This high CMC is probably the biggest risk for consistent (casual) playability in this deck, I would try to get it below 4.
With high CMC creatures and a reanimator package I would try to find ways to bin the fatties and
reanimate,
Tortured Existence is my favorite utility card in that department.
Altar of Dementia is great for filling your own graveyard. Then you can also boost the reanimator package, consider:
animate dead,
reanimate,
whip of erebos.
Dread Return is a great card, but may not ideal in this deck because you are not making that many tokens to have sac fodder for the Flashback cost.
I think you need 1-2 more card draw spells, I only counted 8, and a few of which are high CMC creatures. Consider
Phyrexian Arena or
Night's Whisper. Tutors are amazing but I would not count them as carddraw, they are cantrips and don't net you more cards.
Corrupt seems like a bad removal card, the life gain is not worth all that mana. If you are worried about your life total consider adding
Whip of Erebos (but with Gary,
Exsanguinate and 2 tutors, you should be okay).
When your commander is a PW running
Aether Snap seems like a risk, unless tokens are very popular in your meta.
I would not run
Vampire Hexmage unless you have some combo with it (aka
Dark Depths), if you are running it for PWs in the meta, I would play
the Elderspell instead.
I would swap
In Garruk's Wake or
Necromantic Selection for
Mutilate.
In general I feel like you have a lot of removal and could stand to cut a couple of those cards to add some of the recommendations above.