As someone who has played a lot of Dralnu, I'd recommend including some lands to protect him from burn spells. High Market is your cheapest option, but there's also Phyrexian Tower and Riptide Laboratory (Dralnu has been errata'd to be a "Zombie Wizard"). Reins of Power is another good spell-based way to get around his drawback: "Oh, you cast Blasphemous Act? How about you sacrifice 13 permanents instead?"
I was working on something similar a while ago (last recorded decklist). I ended up making this on mtgo and finishing the remaining cuts, and played it for a few weeks. It was pretty fun, but not very quick.
Due to the slow offensive creation it was too slow for 1v1. It really needed a mass-spell-recursion spell like mizzix's mastery to be effective in multi-player. Metallurgic Summonings had me considering a revisit to the idea, but that seemed to be breaking the theme of the deck too much.
It was very fun to play. If I had a meta that would be compatible with this sort of deck I would absolutely build it IRL so I can show off my odyssey zombie tokens.
edit; Metallic Mimic would be a very easy auto-include in my list. I may want to go update and actually finish that.
I recently built this deck as well, although it was very janky. My basic premise was to use cheap zombies for mana to power out the bigger zombie spells like army of the damned, so sacrificing them to things like ashnod's and phyrexian altar. I think what you'll find is Dralnu wants to use spells and zombie tribal wants creatures and it doesn't quite mesh. There are very few cheaply costed zombie related instants and sorceries that are any good. If you remove the creature focus you may be able to make the deck run more smoothly but at what point is it no longer zombie tribal and just a Dralnu deck? I ended up changing the commander to Thraximundar but it's still one of my lower powered decks. I'm guessing you don't mind it being a bit janky as you're trying to build a Dralnu zombie tribal deck. Anyway, good luck, would love to hear how it turns out.