Illusionist's Bracers would work well with your commander.

Also, Whip of Erebos and Conjurer's Closet is a sweet combo.

Bravo. Love budget edh decks, especially for recommending to friends who are looking to start edh. Sidisi, Undead Vizier is a great engine in this sort of deck, if you're into that kinda thing.

If you add Nim Deathmantle you can go infinite. It combos with Ashnod's Altar which you already have. It can go infinite with Abhorrent Overlord which is already in. It can also make infinite Zombies with Grave Titan.

What you do is cast one of the creatures, Abhorrent Overlord / Grave Titan, sacrifice one token to Ashnod's Altar, then sacrifice the creature you casted to Ashnod's. When you sacrifice the creature, pay the mana you got from Ashnod's to activate Deathmantle's ability bringing the creature back from the Graveyard and starting the process all over again.