What about Nykthos, Shrine to Nyx? You have a lot of devotion to black.

That's a great idea saturnosring, and would really make this steamroll after turn 5 or 6.

Gray Merchant of Asphodel, you can win without even attacking!

ForGot Pack Rat!

That's a good bargain for another sneaky rat, Atony1400.

I'll swap him in for sure.

Figured, he's good!

He is, and even if I don't have the cards to discard to make his ability worthwhile, he can still be sacrificed by Marrow-Gnawer to double my rat count. (and then one of those rats every turn thereafter to keep my rat population growing at an exponential rate.)

If my opponent doesn't have a way to deal with Fear, this deck just swarms right over them.

I did add the Gray Merchant of Asphodel for those decks that DO have a way of dealing with Fear...

Any card along the lines of Dictate of Erebos seems like a decent pick up. Good synergy with Marrow-Gnawer.

Also, Swarmyard.

Patriarch's Bidding anyone? Seems to fit really well here. Also possibly Ink-Eyes, Servant of Oni as some graveyard shenanigans which has synergies with most of your deck.

Hey, Teknetic, that Dictate of Erebos IS a good fit. Sacrifice a rat, get a bunch more rats, AND force my opponent to sacrifice. I like it.

Coinman1863, I have mixed feelings about Patriarch's Bidding. I really like it, and it could easily win me the game. BUT I have run it in other decks, and it can be a VERY costly card to play. Any other tribal deck I play (and my group likes to make decks with a theme to them...) will also greatly benefit from this. Imagine playing with that against Slivers, or Eldrazi, or Allies... shudders It's just too risky.

Ink-Eyes, Servant of Oni on the other hand, when combined with Marrow-Gnawer's fear ability, and her own ninjitsu skills, could really ruin my opponent's day. In particular when paired with the Dictate of Erebos mentioned above. I can just see the turn now...

Marrow-Gnawer and some Rats get ready to attack... Marrow-Gnawer kills a Rat Token, gives me 5 more Rat Tokens... triggers Dictate... opponent sacrifices a creature... Fear-inducing Relentless Rats scurry past my opponent's blockers, and suddenly (with a bunch of kick flipping and Rat-Jitsu Moves, surely) Ink-Eyes stabs them in the face, and I put that creature they just sacrificed into play.

Insult? check
Injury? check
Ninja Rats? double-check

Sounds great, thanks for the help guys!

i think you should put a Magewright's Stone in to untap Marrow-Gnawer for 2x the rats!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Holy rat poop, FLATSO99, that's great!

I'll have to look at what I want to remove for it...

Maybe Relic of Progenitus...

You can pretty much cut all the deathtouch enablers I imagine. You're going to be the aggro deck at the table, and deathtouch doesn't matter on offensive when everything has fear.

The deathtouch has proven imperative against artifact/affinity decks and rival black decks,Teknetic.

Gauntlet of Power could work as a second Caged Sun... Not sure what you would be willing to swap out for it, but figured I would offer it as a suggestion.

Patriarch's Bidding after a board wipe or late game would be sweet. Rotting Rats has a nice "screw everybody" effect. Akroma's Memorial might be nice with all of those nasty critters running around with all of those powers. also you might want way to double your commander's ability, maybe Puppet Strings Illusionist's Bracers or Rings of Brighthearth, you'll be able to make stupid amounts of rats.

good luck.

Second on Rings of Brighthearth--it's also very effective at capitalizing off of Marrow-Gnawer's ability.

I would maybe include a few more non-creature win cons, just in the event something like Magus of the Moat or Lightmine Field comes along. Even Propaganda and Ghostly Prison can be quite a bother if you plan on winning by beating face with rats. Exsanguinate is pretty unsatisfying, but it does the job when you can ramp with Nykthos.

Rather than Death Denied, I would run Rise of the Dark Realms. If it recurs your Gray Merchant, that's game over.

Also, you have basically no draw in here. Rather than run some of these discard cards, which don't seem to serve an essential purpose here, I would up your draw power. Necropotence and Phyrexian Arena are obviously the best, but Vampiric Rites, Dark Prophecy, Read the Bones, Sign in Blood, and Promise of Power are all great budget alternatives to the big boys.

Oh, and if you want infinite rats--Thornbite Staff.

NoSoyYucateco, I'm looking for places to put in some of those cards that make Marrow-Gnawer more effective, I've just go to test them out.

I had been running Phyrexian Arena in addition to Underworld Connections, but with no way of removing Arena, I was losing too much life to it.

The big scary discards I'm running, Nightmare Incursion and Tsabo's Decree are far more than just 'discard from your hand' kind of cards. They're my two heavy hitters. Nightmare Incursion is brutal with the number of swamps I'm running. I get to look at my opponent's entire deck, and find (typically) 5 or 6 cards I really don't want to see. Like those creature breakers that you mentioned, Magus of the Moat and Lightmine Field. Or anything I don't like. Tsabo's Decree is also murder on themed decks, and is particularly horrible for Eldrazi, Dragon, Elf, and Sliver decks. It's the ultimate tribal slayer.

Thornbite Staff is really amusing.

And I think running both Death Denied for a quick recovery, and Rise of the Dark Realms would make me feel a lot better about living through a mass kill effect.

You've given me a lot to consider, thanks for taking the time to think about this!

How much life were you losing to Phyrexian Arena? Most games last around 8-12 turns. If it gets you basically any lifegain card, like Whip or Gray Merchant, or a tutor to grab these in case things get dire, you should have an overall net gain of life.

What do you think about Disciple of Bolas then? When your Relentless Rats get huge, popping one for a big draw/lifegain could be a serious boon.

Hey, that's a nice one NoSoyYucateco, and it hurts the pocket a LOT less.
It could be a GIANT advantage in the case of Pack Rat or Swarm of Rats after Marrow-Gnawer gets the Tide rolling.

Okay... this is starting to really shape up from just a cute deck full of rats into something actually potent...

Coat of Arms recently back-fired on me, so it's been replaced by the much more safe Dragon Throne of Tarkir.

Put that on one plump Relentless Rats and make all the pathetic 1/1 token rats into something really horrible...
(capable of trampling and swarming without counting on the Fear from Marrow-Gnawer)

Dragon Throne of Tarkir is an excellent card that doesn't see nearly enough play in EDH. I use it in a Reki, the History of Kamigawa deck to slap on Molimo, Maro-Sorcerer. And if you play in a tribal-heavy group, it's a bad idea to run Coat of Arms anyway, not to mention that Relentless Rats, by design, really doesn't even need it.

I think you'll be very pleased with Disciple of Bolas if you add it to the deck. You really do need some draw to stay in the game. As it stands now, you're very likely to begin topdecking on turn 6-8 if you don't get Underworld Connections, and that's a dangerous situation to be in.

Now that I know more about your play style, I can maybe offer some better tailored advice.

• You can afford to cut this down to 36 or 37 lands. Your curve is quite low. With enough draw, you'll have no issue with missing land drops. And you'll be less likely to end up with a tiny hand of nothing but swamps.

• With those 5-6 slots you now have available, you can add Disciple of Bolas, Vampiric Rites, Read the Bones, Skullclamp, and maybe Sign in Blood. That will make the deck more consistent, and help keep it from running out of steam.

• Think about Decree of Pain. You do want at least one board wipe, and this one hurts a lot less in a creature-heavy deck. It's also fantastic when you cast it and it causes you to draw into Rise of the Dark Realms. Mutilate can also be pretty great, especially when it your rats are fat enough that it doesn't kill them.

• It's expensive, but Cabal Coffers is kind of a must-include in a mono-black deck. It's far more difficult to remove than Crypt Ghast (which should stay in here, though), and unlike Magus of the Coffers, it goes to work the same turn you play it. You also may want to consider Crypt of Agadeem. If you don't want to drop the dough on Cabal Coffers, but someone else in your group plays it, you can go with the much cheaper Thespian's Stage to copy theirs. Or, you can run both, and have two Coffers. There are a few other lands you might want to consider, such as Reliquary Tower, Temple of the False God, Ghost Quarter, etc..., but if you go with too many non-basics, you'll want Urborg, Tomb of Yawgmoth, which recently ballooned in price.

• With several cards relying on you to control lots of swamps, Wayfarer's Bauble and Solemn Simulacrum are great cards. They ramp you, they up your swamp count, and they ever-so-slightly decrease the odds that you'll draw a swamp when you don't need one. Play Solemn Simulacrum, Skullclamp it, and then trash it to Vampiric Rites (or wait for it to die of natural causes) and you've just drawn 3-4 extra cards, and gained a life and an additional swamp on the battlefield. Not too shabby for a play that can easily be pulled off by turn 5 with the right hand.

Anyway, sorry for the novel. I love mono-black, and it's the build I have the most experience with.

Fun thought, though not one I would probably attempt--Thornbite Staff your Marrow-Gnawer, then Bitter Ordeal.

Ashnod's Altar is always good. Obelisk of Urd is another good card to pump your rats.

Oh--one last thought. Now that you've got some ramp going in here, Diabolic Revelation could be a better tutor option than Diabolic Tutor.

How would Thornbite Staff make infinite rats?