I like the deck. A few things that I would change up (personal preference)
Cremate can come out.
Scavenging Ooze does the job but better. I would replace with
Raven's Crime. with
The Gitrog Monster,
Dakmor Salvage, and
Raven's Crime, you can cast the
crime for as much black mana that you have available. Another personal preference would be to not run Tasagir. While he is a good card, you may run into the position where you have to
exile some of your spells that you may not want to in order to cast him. You should have more than enough
dredge to feed the monster and not really need his activated ability. I would replace him with 1 of 3 things, 1 = a couple more lands. (More frog triggers, better
odds of hitting lands on turn, and easy fodder for
Zombie Infestation). 2 = More removal (
abrupt decay is good and so is dissmember. (maybe consider
Go for the throat, or
victim of night depending on your local meta) 3 = (my favorite of the options)
Bloodghast. (easy recursion from being
dredge, killed, or discarded with infestation). All of these are excelent options in my opinion. I also feel that 2-3 Zombie infestations is enough, but that goes into how I play my gitrog monster decks. Best of luck!