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?

Marrow-Gnawer taps, creating rats and putting one in the graveyard. Staff Untaps him. Repeat. Apply exponent. Make chittering sounds. Zer0w

but tokens dont go in the graveyard right?

or will you sac non tokens

Tokens do go to the graveyard if/when appropriate, but they cease to exist once they're there. They still trigger relevant abilities when they die.

ok i see

Thank you for explaining that, Epochalyptik.

Okay, NoSoyYucateco, after playing things through a few times, and considering all of your recommentations, I've made the following changes:

Removed Demonic Tutor and added Diabolic Revelation. I know you suggested removing Diabolic Tutor instead, but this is also a $$$ decision, in addition to a gameplay one.

Removing 5 Swamps for:

• Adding Vampiric Rites and Skullclamp for draw. (I could have sworn Skullclamp was illegal, but it looks like it's ONLY legal in EDH.)

• Adding Mutilate for mass-removal, and also the killing of indestructible, hexproof, shrouded Commanders. Unlike Decree of Pain this thing can kill almost everything there is (barring regeneration, of course.)

• Adding (unsuggested, but more an oversight on my part) the Commander standard Swiftfoot Boots for Marrow-Gnawer to wear. I realized he's far too vulnerable to stealing, killing, and otherwise doing horrible things to. Now that more of the deck is built with his mechanic in mind, having him able to use said mechanic the turn he arrives thanks to haste and living to talk about it with hexproof, I think it's the right call.

• Finally, because of what you discussed with needing win-cons that don't require victory through a million rat bites... I'm going to playtest out your half-joking suggestion of Bitter Ordeal. At the very least, it'll give me another chance to pull a card (or cards) I don't like from my opponent's deck, I also have the possibility of a mill-victory, which could be really nice in the case of things like Worship and Platinum Emperion.

I'll let you know how it's playing out, but so far I'm really enjoying the changes.

Thanks again!

This is really cool. Just a quick question, though. Correct me if I'm wrong, but you could- in good theory- play all your Relentless Rats in one turn using Thrumming Stone right? I'm not too familiar with "ripple" but, if I understand the text, every time you play another rat off ripple that rat will trigger another ripple and keep the string going. These triggers will stack up if you hit multiple rats in one ripple and you should be able to go through most of your deck and get some 31/31 rats on the field, right?

Once again, really cool deck even if that's not how ripple works. Flavorful, remorseless, and fun. +1 and happy trails.

Yep, jakeelephant006, that's exactly how it works, and unless your opponent has a nice board-wipe in their hand (which you hopefully have un-tutored out for them by then) then next turn you're going to hit them like a giant bag of... well... a giant bag of rats.

Potentially 31/31 Rats, with Fear, Deathtouch, and Lifelink, although that's really unlikely. Even if you only get them to 13/13 or so, that's still 11x 13/13 creatures attacking...

Akroma's Memorial lets them attack that turn, giving your opponents even less chance of wrathing. Another card which can be very powerful is Sword of the Paruns. With oyur commander, it allows you to almost double your rat count per 3 mana invested. and it gives you a way of buffing them for both defensive or offensive purposes.

That sword is very tempting, enpc, though I'm starting to get to that point where each cut kind of hurts. What would you remove for it? It's essentially a more expensive Magewright's Stone, but with the the added +2/0, which is not to be ignored.

Akroma's Memorial would have to replace Liliana of the Dark Realms, since it would stop me from using her second power to buff my own creatures.
Ultimately, though it IS an amazing card, something just doesn't feel right about running a Protection from Black, angelic monument in a mono-black deck focused on a filthy underworld.

I had also considered the very scary Eldrazi Monument for this deck, and discounted it for pretty much the same reason.

That sword though... Going to have to look closely at that...

I dont think you're going to run into the problem of wanting to buff creatures with Liliana of the Dark Realms while having Akroma's Memorial in play often enough for it to be a concern. It does feel a bit weird, but I thing the pros greatly outweigh the cons.

I was weighing them against each other, enpc, since the memorial would have to fit SOMEWHERE.

You will probably seldom, if ever, use Liliana's -3 to buff a rat. She'll be there to grab you a swamp, and for spot removal. Since you have everything on the ground, she's pretty likely to be taken out by flyers before you can ever ult her. Which is fine. She's a good card even without her ultimate.

Honestly, Akroma's Memorial is your best bet to actually pull off a huge combat damage win. It's a pricy card, but you're far more likely to catch opponents off guard by pumping out a gazillion tokens with haste than you are removing the board wipes from their deck. I know it's weird flavor-wise, but it's extremely effective.

Though you have the potential to get some extremely big, unblockable rats here, so a simple Lightning Greaves or Swiftfoot Boots could easily be enough to have fatal on an opponent after you Thrumming Stone.

Personally, I would either drop Gray Merchant of Asphodel or Exsanguinate for Akroma's Memorial. They both functionally do the same thing and both hinge on certain cards. Of the two and i nthe current build, I would cut Exsanguinate. The main way that you'll get an instant kill with it is by using Nykthos, Shrine to Nyx as you're not running Cabal Coffers or Ashnod's Altar.

This means that you need to have 1) a high deviation to black, 2) have Nykthos and 3) have Exsanguinate. However, with Gray Merchant of Asphodel you need 1) a high devotion o black and 2) gary. One less card required, making him the better play.

I just noticed you added Bitter Ordeal. If you are going to go that route, I'd have another sac outlet, frankly, because at sorcery speed, it's not going to do a ton without Thornbite Staff, since you aren't doing a lot of wrathing, and your rats often won't be dying to combat damage.

Viscera Seer is a fantastic card that lets you sac at instant speed, paying no mana, in exchange for scrying. With him, you could get some really pretty decent Bitter Ordeals off (even scrying to dig down for it, if necessary.) Plus he's just an all around great card for when a board wipe is on the stack, or worse, your rats are about to get the Merciless Eviction treatment.

If you think he'd be a good addition, I can think about where you might make a cut to make room for him.