I'm not going to critique the creature list too much given that I run a very different style, but I think that I can give some advice on your instants/sorceries, artifacts, and enchantments.
Rooftop Storm seems like a necessity in a strongly zombie-based list. It gives you a lot of tempo and helps Grimgrin get replayed.
Unhallowed Pact seems like it could be Nim Deathmantle or Darksteel Plate or Shield of Kaldra. Same sort of effect and are all a bit more resilient in U/B (there is artifact recursion in blue, but no enchantment recursion. Fool's Demise seems to be a strictly better version of this card that will serve its role just fine.
I'd be careful with Dark Prophecy. It can give you massive card advantage, but at the same time, it can make you lose a lot of life when you don't want to. What would happen if someone wrath'd your Army of the Damned late in the game? It could be backbreaking. I'd look at Phyrexian Arena for the same sort of draw without limiting yourself. Grimgrin also has the potential to infinitely sac Gravecrawler if you have Rooftop Storm and Dark Prophecy would screw you over in that situation since you have no ability to kill enchantments and what little ways you might have, you wouldn't want to waste on yourself.
Sever the Bloodline is an absolutely incredible removal spell. It gives you exile in black and also works as a sort of Maelstrom Pulse effect. Excellent against token strats and has flashback on it.
I like what Tragic Slip does for the deck and wouldn't remove it, but you should look at potentially putting a couple counterspells in the deck. Doesn't have to be more than about two, but if you're running U/B and have very limited responses to things like artifacts, enchantments, or planeswalkers other than countering it on the stack, you need to be able to respond to those threats. Dissipate, Soul Manipulation, Hinder, Spell Crumple, Counterspell, are my best suggestions.
Some of your cards bring back all creatures from all graveyards, I think that it would be good to have more graveyard hate, i.e. Tormod's Crypt or Nezumi Graverobber to protect your spells from benefiting your opponents to much.
Phthisis either seems too expensive to me or too slow. If you want a blowout lose life effect, I'd suggest Exsanguinate. If you want removal, I think there are more efficient cards that could fill that slot. It's also a sorcery, which doesn't help too much either.
You have 13 swamps in deck and I'll guess you won't consistently have even half of them so, without Urborg on the field, Mutilate doesn't do a ton for you. I'd consider, potentially, putting Black Sun's Zenith in instead.
Hope this feedback helps. Just what I had off the top of my head.
I'm not going to critique the creature list too much given that I run a very different style, but I think that I can give some advice on your instants/sorceries, artifacts, and enchantments.
Rooftop Storm seems like a necessity in a strongly zombie-based list. It gives you a lot of tempo and helps Grimgrin get replayed.
Unhallowed Pact seems like it could be Nim Deathmantle or Darksteel Plate or Shield of Kaldra. Same sort of effect and are all a bit more resilient in U/B (there is artifact recursion in blue, but no enchantment recursion. Fool's Demise seems to be a strictly better version of this card that will serve its role just fine.
I'd be careful with Dark Prophecy. It can give you massive card advantage, but at the same time, it can make you lose a lot of life when you don't want to. What would happen if someone wrath'd your Army of the Damned late in the game? It could be backbreaking. I'd look at Phyrexian Arena for the same sort of draw without limiting yourself. Grimgrin also has the potential to infinitely sac Gravecrawler if you have Rooftop Storm and Dark Prophecy would screw you over in that situation since you have no ability to kill enchantments and what little ways you might have, you wouldn't want to waste on yourself.
Sever the Bloodline is an absolutely incredible removal spell. It gives you exile in black and also works as a sort of Maelstrom Pulse effect. Excellent against token strats and has flashback on it.
I like what Tragic Slip does for the deck and wouldn't remove it, but you should look at potentially putting a couple counterspells in the deck. Doesn't have to be more than about two, but if you're running U/B and have very limited responses to things like artifacts, enchantments, or planeswalkers other than countering it on the stack, you need to be able to respond to those threats. Dissipate, Soul Manipulation, Hinder, Spell Crumple, Counterspell, are my best suggestions.
Some of your cards bring back all creatures from all graveyards, I think that it would be good to have more graveyard hate, i.e. Tormod's Crypt or Nezumi Graverobber to protect your spells from benefiting your opponents to much.
Phthisis either seems too expensive to me or too slow. If you want a blowout lose life effect, I'd suggest Exsanguinate. If you want removal, I think there are more efficient cards that could fill that slot. It's also a sorcery, which doesn't help too much either.
You have 13 swamps in deck and I'll guess you won't consistently have even half of them so, without Urborg on the field, Mutilate doesn't do a ton for you. I'd consider, potentially, putting Black Sun's Zenith in instead.
Hope this feedback helps. Just what I had off the top of my head.
The problem that I have with Rooftop Storm is that it enables an infinite combo with Gravecrawler and Grimgrin, Corpse-Born. I do not mind playing against decks that contain infinite combos, but I do prefer to build and pilot decks that don't. It's just who I am and I like the restriction it gives my decks. This isn't to say that this card is bad, though. In a dedicated tribal build this card is the nuts, and combined with any sort of card draw engine it has the chance to flip your deck onto the battlefield. I've used it before and I love it, but the temptation of tutoring for it or Gravecrawler is too much for me, and (for me) it doesn't feel rewarding to want to win that way every time. It's a shame because I own a foil copy.
Hero's Downfall is a good suggestion. I always find that, when I build decks, that I include ways to rid creatures with other creatures, but I always find myself asking for help from the table after a board wipe. Adding more straight kill spells and one that also targets planeswalkers is a very worthy inclusion. Since you've mentioned it before and it shares the same CMC, it will come in for Unhallowed Pact.
Black Sun's Zenith I know I have a copy of this somewhere, so when I find it I will swap it out for Mutilate. You make an excellent point with the lack of swamps and having to rely on Urborg, Tomb of Yawgmoth.
Phthisis This was in the deck as another kill spell but to also hose my friend who plays Trostani Lifegain with Serra Avatar. I figure that I can probably swap it with a better spell, but your other comment about not having a way to deal with enchantments or artifacts once they hit the field. So, since it also has the same CMC, I am swapping it with Spine of Ish Sah. It answers any permanent and is self recurring. To get the most out of it I'll need a way to repeated put it in the graveyard. Since sacrificing is a theme in the deck, Trading Post can come in for Wight of Precinct Six because currently it's not helping me. It sacs artifacts and creatures, and recurs artifacts and makes a Goat token. After all, sacrificial goats are the best kind of offering.
Dark Prophecy is a card that I really enjoy playing with, despite the dangerous downsides. The only part I don't like about it is the fact that it costs triple B to play. I've considered tossing in Phyrexian Arena before, but it's so damn abundant that I'm just sick of seeing it. I have been thinking of adding Mystic Remora because it only costs 1 U and will draw way more cards than I spent to cast it. The other options are Greed, Erebos, God of the Dead, Necropotence, and Rhystic Study. Greed can get costly after a while, but it is controlled draw which is attractive. Erebos does it better by being indestructible and preventing life gain which is useful in my meta. However, there's a new Erebos deck in the meta so I'm not sure if I want to double dip. Necropotence has the same problem as Dark Prophecy by costing triple B, and it shuts off other draw, so I don't think it would be useful here. I've never used it so I can't be for certain. Rhystic Study is another option, a card which I have multiple copies of. Saying "Rhystic Trigger" multiple times a turn can get quite repetitive, and later in the game people won't mind paying the extra 1.
Unfortunately since I would like to renaimate some of my opponents' creatures anything with tuck won't help me , even if it means never tucking opposing generals. There is Soul Manipulation as you've mentioned which I still have a copy of lying around. This can come in for Crypsis. I do like the idea of Dissipate to remove problem enchantments and artifacts from the game, but I'm torn between it and because the minor draw fixing looks appealing and I can always reanimate opposing artifacts with Geth, Lord of the Vault. I could just as well add SDT or Crystal Ball, but unless I'm working with a top deck manipulation theme I really don't see a need for them. Thoughts?
That Phthisis interaction is pretty lol-worthy. I almost think you should leave it in just for that.
Top deck manipulation is always good if you have instant speed answers, making SDT valuable even without any sort of dedicated abuse (i.e. instant speed tutors or miracle cards).
I really think that Rooftop Storm should be in the list. Honestly, I know it can infinite combo, but the worthwhile synergy outside of that does so much more for your list that it is worth it. Also, it bears mentioning, that even if it "infinite combos", for the purpose of killing someone with Grimgrin, you still have to connect with them through combat, and you have to do the same thing on consecutive turns in order to win via killing multiple opponents. Even without that though, running it just for the zombies you have seems pretty worthwhile. I hate combos just for the sake of having combos, but I feel RS is different.
Rooftop Storm seems like a necessity in a strongly zombie-based list. It gives you a lot of tempo and helps Grimgrin get replayed.
Unhallowed Pact seems like it could be Nim Deathmantle or Darksteel Plate or Shield of Kaldra. Same sort of effect and are all a bit more resilient in U/B (there is artifact recursion in blue, but no enchantment recursion. Fool's Demise seems to be a strictly better version of this card that will serve its role just fine.
I'd be careful with Dark Prophecy. It can give you massive card advantage, but at the same time, it can make you lose a lot of life when you don't want to. What would happen if someone wrath'd your Army of the Damned late in the game? It could be backbreaking. I'd look at Phyrexian Arena for the same sort of draw without limiting yourself. Grimgrin also has the potential to infinitely sac Gravecrawler if you have Rooftop Storm and Dark Prophecy would screw you over in that situation since you have no ability to kill enchantments and what little ways you might have, you wouldn't want to waste on yourself.
Sever the Bloodline is an absolutely incredible removal spell. It gives you exile in black and also works as a sort of Maelstrom Pulse effect. Excellent against token strats and has flashback on it.
I like what Tragic Slip does for the deck and wouldn't remove it, but you should look at potentially putting a couple counterspells in the deck. Doesn't have to be more than about two, but if you're running U/B and have very limited responses to things like artifacts, enchantments, or planeswalkers other than countering it on the stack, you need to be able to respond to those threats. Dissipate, Soul Manipulation, Hinder, Spell Crumple, Counterspell, are my best suggestions.
Go for the Throat could easily be Hero's Downfall.
Some of your cards bring back all creatures from all graveyards, I think that it would be good to have more graveyard hate, i.e. Tormod's Crypt or Nezumi Graverobber to protect your spells from benefiting your opponents to much.
Phthisis either seems too expensive to me or too slow. If you want a blowout lose life effect, I'd suggest Exsanguinate. If you want removal, I think there are more efficient cards that could fill that slot. It's also a sorcery, which doesn't help too much either.
You have 13 swamps in deck and I'll guess you won't consistently have even half of them so, without Urborg on the field, Mutilate doesn't do a ton for you. I'd consider, potentially, putting Black Sun's Zenith in instead.
Hope this feedback helps. Just what I had off the top of my head.
EDH:
G[cEDH] Selvala, Heart of the StormG
URW[cEDH] Narset, the Last AirmericanURW
GWUSt. Jenara, the ArchangelGWU
UBGrimgrin, Chaos MarineUB
GOmnath, Mana BaronG
URWNarset, Justice League AmericaURW
GWUBAtraxa, Countess of CountersGWUB
GWUEstrid, Enbantress PrimeGWU
Hero's Downfall is a good suggestion. I always find that, when I build decks, that I include ways to rid creatures with other creatures, but I always find myself asking for help from the table after a board wipe. Adding more straight kill spells and one that also targets planeswalkers is a very worthy inclusion. Since you've mentioned it before and it shares the same CMC, it will come in for Unhallowed Pact.
Black Sun's Zenith I know I have a copy of this somewhere, so when I find it I will swap it out for Mutilate. You make an excellent point with the lack of swamps and having to rely on Urborg, Tomb of Yawgmoth.
Phthisis This was in the deck as another kill spell but to also hose my friend who plays Trostani Lifegain with Serra Avatar. I figure that I can probably swap it with a better spell, but your other comment about not having a way to deal with enchantments or artifacts once they hit the field. So, since it also has the same CMC, I am swapping it with Spine of Ish Sah. It answers any permanent and is self recurring. To get the most out of it I'll need a way to repeated put it in the graveyard. Since sacrificing is a theme in the deck, Trading Post can come in for Wight of Precinct Six because currently it's not helping me. It sacs artifacts and creatures, and recurs artifacts and makes a Goat token. After all, sacrificial goats are the best kind of offering.
Dark Prophecy is a card that I really enjoy playing with, despite the dangerous downsides. The only part I don't like about it is the fact that it costs triple B to play. I've considered tossing in Phyrexian Arena before, but it's so damn abundant that I'm just sick of seeing it. I have been thinking of adding Mystic Remora because it only costs 1 U and will draw way more cards than I spent to cast it. The other options are Greed, Erebos, God of the Dead, Necropotence, and Rhystic Study. Greed can get costly after a while, but it is controlled draw which is attractive. Erebos does it better by being indestructible and preventing life gain which is useful in my meta. However, there's a new Erebos deck in the meta so I'm not sure if I want to double dip. Necropotence has the same problem as Dark Prophecy by costing triple B, and it shuts off other draw, so I don't think it would be useful here. I've never used it so I can't be for certain. Rhystic Study is another option, a card which I have multiple copies of. Saying "Rhystic Trigger" multiple times a turn can get quite repetitive, and later in the game people won't mind paying the extra 1.
Sever the Bloodline can definitely come in for Go for the Throat, I'll pick up a copy somewhere on the cheap.
Unfortunately since I would like to renaimate some of my opponents' creatures anything with tuck won't help me , even if it means never tucking opposing generals. There is Soul Manipulation as you've mentioned which I still have a copy of lying around. This can come in for Crypsis. I do like the idea of Dissipate to remove problem enchantments and artifacts from the game, but I'm torn between it and because the minor draw fixing looks appealing and I can always reanimate opposing artifacts with Geth, Lord of the Vault. I could just as well add SDT or Crystal Ball, but unless I'm working with a top deck manipulation theme I really don't see a need for them. Thoughts?
Top deck manipulation is always good if you have instant speed answers, making SDT valuable even without any sort of dedicated abuse (i.e. instant speed tutors or miracle cards).
I really think that Rooftop Storm should be in the list. Honestly, I know it can infinite combo, but the worthwhile synergy outside of that does so much more for your list that it is worth it. Also, it bears mentioning, that even if it "infinite combos", for the purpose of killing someone with Grimgrin, you still have to connect with them through combat, and you have to do the same thing on consecutive turns in order to win via killing multiple opponents. Even without that though, running it just for the zombies you have seems pretty worthwhile. I hate combos just for the sake of having combos, but I feel RS is different.
EDH:
G[cEDH] Selvala, Heart of the StormG
URW[cEDH] Narset, the Last AirmericanURW
GWUSt. Jenara, the ArchangelGWU
UBGrimgrin, Chaos MarineUB
GOmnath, Mana BaronG
URWNarset, Justice League AmericaURW
GWUBAtraxa, Countess of CountersGWUB
GWUEstrid, Enbantress PrimeGWU