> Introduction

This deck was born while I was looking for Doomsday piles to put into my first Marchesa's deck.
I found this article about Doomsday with Grenzo, Dungeon Warden as a commander, it was very well explained and came with a decklist too (I'd put the link, but I think the website has been taken down time ago).
I thought it was a really cool idea and immediately started to brew my own version. It came together quite fast and easily, and in a matter of few months I already had a stable build.
It was quite different from the original, though, since that was aimed for competitive 1-vs-1, while mine was intended for multiplayer.
At some point, I had to decide if I wanted to push it for competitive play or keep it at a more casual level. I finally decided for the second option because I've never really played competitive, so I didn't feel like I was up to the task. Moreover, even if I wasn't planning to build it in the real life, many of the cards (Badlands, Mana Crypt, Imperial Seal...) were far too expensive to justify the whole thing.
By the way, the deck is still quite strong. I'd say, in a rating scale from 1 to 5 (where 1 means "casual" and 5 means "competitive") that this deck scores somewhere between 3 and 4.

> Gameplay

The deck mostly relies on using Grenzo's ability to flip creatures from the bottom of your library.
With the amount of creatures in the deck, you roughly have 1/3 of chances to actually flip one. Moreover, most of them have power 2 or less, so you won't need to pump Grenzo to flip them.
In fact, you generally want your commander out as soon as possible (i.e. with no counters on it) although, if you have Teferi's Puzzle Box or any other tool that could help you to stack the bottom of your library, go for it first.
Normally Grenzo doesn't draw too much attention. He's likely to stay on the battlefiled several turns, unless your opponents already know what the deck is up to. Nonetheless, there is no need to expose him if you're not planning to activate him any time soon.
The best time to flip a card is generally at the end of the last turn before you get to untap, so that your creatures don't die to sorcery-speed wrath effects. If you have Thran Turbine out you can wait until your upkeep, but flipping after your draw step is a risk, because if you happen to flip Maralen of the Mornsong all our opponents will get to tutor whatever they want before you.
The two main win conditions are Doomsday and Insidious Dreams. Each of these cards allow you to stack the bottom of your library with one of the many combos in the deck.
In theory, you could win as soon as turn 3, provided you cast Grenzo, Dungeon Warden on turn 2 and follow up with Doomsday the next turn, with something like Dark Ritual or Sol Ring that lets you have 2 spare mana open.
In some situation, you could even spend turn 1 casting Vampiric Tutor to search for missing combo pieces and still be able to go off at turn 3.
As a downside, not having access to blue, you'll have a hard time protecting Doomsday when you're trying to go off.
By the way, the most problematic issue is against stax and other control strategies. Cards like Torpor Orb or Cursed Totem can single-handedly shut down the entire strategy.
Moreover, it's worth noting that Grenzo's ability isn't affected by graveyard hate like Rest in Peace. The creature still gets onto the battlefield even if it didn't touch the bin.

> Combos

The deck runs many combos. In fact, it's not that unusual to accidentally assemble one of them by just randomly flipping cards with Grenzo.
Here's the list:

> Kiki-Jiki, Mirror Breaker + Zealous Conscripts

This is probably the easiest combo to assemble, since it only requires 2 cards and you only need to find a way to pump Grenzo's power by 1 to flip them from the bottom of your library.
The only disadvantage is that you have to pass through your combat phase, so you can't win at instant speed.
For those who don't know the combo, you basically tap Kiki-Jiki to copy Zealous Conscripts. When the token enters the battlefield you target Kiki-Jiki, gaining control (unrelevant) and untapping it. You can now repeat the process as many times as you want, making infinite hasty tokens and attacking everyone for lethal damage.

> Kiki-Jiki, Mirror Breaker + Skirk Prospector + Lightning Crafter

This combo requires 3 cards but can win at instant speed, since it relies on direct damage and doesn't need to pass through the combat phase.
There are other sacrifice outlets in the deck that you can use (Viscera Seer and Ashnod's Altar), but Skirk Prospector is slightly better because it nets you mana in the process and it's a goblin. This is particularly important because, as you'll get to see in a moment, this deck has several ways to fetch goblins and there are several cards that care about goblins in general.
The combo works as follows: you copy Lightning Crafter with Kiki-Jiki, the token champions Kiki-Jiki, then you tap it to deal 3 damage and sacrifice it. Kiki-Jiki returns to play untapped, so that you can repeat the process as many times you want until you kill everybody.

> Mikaeus, the Unhallowed + Triskelion

This combo is often referred to as Mike & Trike.
It requires only 2 cards and can win at istant speed. It's normally the combo you go for when you have Victimize in your hand, since Mikaeus' power of 5 makes him especially tricky to flip with Grenzo (as you'll see, this deck has some way to do that nonetheless).
How the combo works: Triskelion is a 2/2 (because it's pumped by Mikaeus) with three +1/+1 counters on it. You remove one counter to ping something for 1 damage, then you use the rest to kill Triskelion itself. It will come back with 4 counters thanks to undying. You can now ping anything for 2 and keep killing Triskelion, so that it will return each time with new counters on it, until you get to kill everybody.

> Murderous Redcap + Skirk Prospector + Metallic Mimic

This is the most recent addition to Grenzo's arsenal.
It's essentialy a variant of the previous combo, with one more card but the upside that you don't need to pump Grenzo to flip it, since all creatures have power 2 or less.
In fact, you can swap Metallic Mimic for Mikaeus, the Unhallowed and Skirk Prospector for Viscera Seer or Ashnod's Altar, and still get the same result.
Here, you sacrifice Murderous Redcap so that it will come back to play because of persist, but the -1/-1 counter will be elided with the +1/+1 counter granted by Metallic Mimic. You can repeat the process infinite times, shooting everybody to death with Redcap's triggered ability.

> Maralen of the Mornsong + Stranglehold

This isn't technically a combo, since you're not winning right away, but if it gets unanswered your opponents will be prevented from drawing new cards for the rest of the game.
Also, it could be considered a 1-card combo, since you only need to flip Maralen and she will tutor for Stranglehold by herself. Therefore, it's a good pile for Insidious Dreams.
If you have both cards in play, on your turn you'll pay 3 life to tutor for whatever, on other players' turn they'll still pay 3 life but can't tutor for anything because of Stranglehold.
As I said before, Maralen has to hit the battlefield just before your draw step for this to work. Additionally, make sure to have enough mana to cast Stranglehold on that same turn.

> Doomsday Piles

Here I will detail some notable piles you can stack with Doomsday.
It's important to note that they're meant to be a guideline and not an exhaustive list. In fact, sometimes you could have some combo pieces already on the battlefield (or in your hand), other times you could have more or less mana available for extra protection and so on. You should adapt them to the game situation.
Cards are listed in the order they would be flipped by Grenzo, so the first card will go on the bottom and the last on top of your library.

> Priest of Gix - Kiki-Jiki, Mirror Breaker - Mad Auntie - Zealous Conscripts - <whatever>

This is the basic pile and the cheapest one, since it only requires 4 cards and 2 mana to go off.
Steps to follow:

• pay 2 mana to flip Priest of Gix and net 3 black mana in exchange.
• use 2 of those 3 mana to flip Kiki-Jiki, Mirror Breaker, tap it to copy Priest of Gix and net 3 more black mana (4 total).
• use 2 of that mana to flip Mad Auntie and pump Grenzo, Dungeon Warden.
• now that Grenzo is a 3/3, you can use the last 2 mana to flip Zealous Conscripts and go infinite with Kiki-Jiki.

> Priest of Gix - Kiki-Jiki, Mirror Breaker - Murderous Redcap - Skirk Prospector - Metallic Mimic

This pile still requires only 2 mana to go off.
It starts like the previous one, but uses Kiki-Jiki only to make mana and goes for Murderous Redcap combo instead.
Steps to follow:

• pay 2 mana to flip Priest of Gix and net 3 black mana in exchange.
• use 2 of those 3 mana to flip Kiki-Jiki, Mirror Breaker, tap it to copy Priest of Gix and net 3 more black mana (4 total).
• use 2 of that mana to flip Murderous Redcap, shoot whatever you want for 2 damage.
• use the last 2 mana floating to flip Skirk Prospector, then sacrifice Kiki-Jiki and the Redcap to net 2 red mana.
• in response to Redcap's persist trigger, use that mana to flip Metallic Mimic.
• Murderous Redcap will return to the battlefield with no counters, so you can go infinite.

> Workhorse - Clone Shell - Mikaeus, the Unhallowed - Triskelion - Viscera Seer

This pile requires 4 mana to go off, therefore compares unfavorably with the others.
In general I don't recommend it, but there could be some scenario where you would need it, so it's good to know it exists.
Steps to follow:

• pay 2 mana to flip Workhorse.
• remove 2 counters from Workhorse to flip Clone Shell, look at the other creatures and imprint Mikaeus, the Unhallowed.
• remove the last 2 counters from Workhorse to flip Triskelion.
• pay 2 more mana to flip Viscera Seer, then sacrifice Clone Shell to get Mikaeus back to play.

> Workhorse - Clone Shell - Lightning Crafter - Kiki-Jiki, Mirror Breaker - Viscera Seer

It's essentially the previous pile, with Kiki-Jiki instead of Mike & Trike.
I don't recommend it either.

> Ransack the Lab - Victimize - Mikaeus, the Unhallowed - Triskelion.

This pile doesn't need Grenzo to go off.
The only requirement is to have 3BB mana open and one creature on the battlefield.
Steps to follow:

• draw Ransack the Lab and cast it, keeping Victimize while dropping Mikaeus, the Unhallowed and Triskelion to the graveyard.
• cast Victimize to reanimate them and win the game.

> Insidious Dreams Piles

Many of the piles for Insidious Dreams are essentially the same for Doomsday, with an additional card to put the rest on the bottom of your library.
Most of the piles require you to draw a card, so the better moment to cast Insidious Dreams is right before starting your turn.
Unfortunately, you won't have slots available for mana acceleration, so the focus here is more on the cards you have to discard to pay for Insidious Dreams' additional cost.

> Howltooth Hollow/Spinerock Knoll - Kiki-Jiki, Mirror Breaker - Mad Auntie - Zealous Conscripts

This is the Insidious Dreams version of Doomsday's first pile.

• draw the hideaway land and play it.
• put Kiki-Jiki, Mad Auntie and Zealous Conscripts on the bottom of your library, hiding away the fourth card.
• flip the cards with Grenzo and win the game (you need 6 mana to do so).

> Temple of Malice - Brass Herald - Kiki-Jiki, Mirror Breaker - Zealous Conscripts

This is essentially the previous pile, with Temple of Malice instead of the hideaway land.

• draw Temple of Malice and play it.
• scry the top card of your library, putting Brass Herald on the bottom.
• flip Brass Herald, naming rogue to pump Grenzo, then put the rest on the bottom of your library.
• flip Kiki-Jiki, Mirror Breaker and Zealous Conscripts, then go infinite.

> Howltooth Hollow/Spinerock Knoll - Murderous Redcap - Skirk Prospector - Metallic Mimic

Same as the first pile, but with Murderous Redcap combo instead.
It costs 1 less mana, because you get to sacrifice the Redcap to Skirk Prospector during the process.

> Temple of Malice - Clone Shell - Mikaeus, the Unhallowed - Viscera Seer - Triskelion

This pile requires one more card to go off, so I don't recommend it.

• draw Temple of Malice and play it.
• scry the top card of your library, putting Clone Shell on the bottom.
• flip Clone Shell, imprint Mikaeus and put the rest on the bottom.
• flip Viscera Seer, then sacrifice Clone Shell to get Mikaeus back to play.
• flip Triskelion and go infinite.

> Temple of Malice - Clone Shell - Lightning Crafter - Viscera Seer - Kiki-Jiki, Mirror Breaker

Same as before, but with Kiki-Jiki instead of Mike & Trike.

> Howltooth Hollow/Spinerock Knoll - Brass Herald - Goblin Recruiter

This pile only requires 3 cards, although you need 8 mana to set it up.
The trick here is to use the first pile to fetch a second one (namely, the one with only goblins) and go off from that.

• draw the hideaway land and play it.
• look at the top of your library, putting Brass Herald and Goblin Recruiter on the bottom.
• flip Brass Herald, naming Rogue to pump Grenzo.
• in response to Brass Herald's trigger, flip Goblin Recruiter and fetch the second pile:
  Skirk Prospector - Sling-Gang Lieutenant - Kiki-Jiki, Mirror Breaker - Lightning Crafter
  • flip Skirk Prospector (you've paid 6 mana so far), then sacrifice Goblin Recruiter to net 1 red mana.
  • pay 1 more mana (7 so far) to flip Sling-Gang Lieutenant, then sacrifice it together with its tokens to net 3 mana.
  • use 2 of that mana to flip Kiki-Jiki, Mirror Breaker.
  • pay 1 more mana (8 total) to flip Lightning Crafter and go infinite.

> Howltooth Hollow/Spinerock Knoll/Temple of Malice - Maralen of the Mornsong

This can be actually pulled off any time you happen to flip Maralen of the Mornsong.

• draw the land and play it.
• put Maralen of the Mornsong on the bottom of your library.
• at the end step before starting your turn, flip Maralen.
• on your draw step, tutor for Stranglehold and cast it to lock the board.

> Ransack the Lab - Victimize - Mikaeus, the Unhallowed - Triskelion.

This pile doesn't need Grenzo to go off.
The only requirement is to have 3BB mana open and one creature on the battlefield.
Steps to follow:

• draw Ransack the Lab and cast it, keeping Victimize while dropping Mikaeus, the Unhallowed and Triskelion to the graveyard.
• cast Victimize to reanimate them and win the game.

> Other Interactions

> Mikaeus, the Unhallowed + Workhorse + Viscera Seer

This combo doesn't wins you the game but gives you infinite mana, which is kind of the same.
You'll almost always prefer Mike & Trike over this but again, it's nice to know it exists.
It works by removing all the counters from Workhorse for mana, then sacrificing it to Viscera Seer (it's a 1/1 because of Mikaeus). Workhorse will come back thanks to undying, so you can rinse and repeat as many times you want.
You can use Ashnod's Altar instead of Viscera Seer for yet more mana, if you want.

> Moggcatcher

People often overlook this card, but by resolving this critter you're basically putting a clock of 2 turns on the game.
Of course, you have to wait for a whole round table before starting to use it (because of summoning sickness), but after that you can follow these steps:

• at the end step before starting your turn, tap Moggcatcher to fetch Kiki-Jiki, Mirror Breaker.
• tap Kiki-Jiki to copy Moggcatcher, the token will survive through your turn because the end step already passed.
• during your turn, tap both the original Moggcatcher and the token to fetch Skirk Prospector and Lightning Crafter (you need 6 mana to do so).
• win the game.

> Wort, Boggart Auntie + Gempalm Incinerator

This falls into the casual side of this deck. In fact, Wort was one of the reasons that made me steer away from a full-competitive list.
I like the card, it's pretty solid by itself. Most of the creatures in this deck have weak stats and tend to die to whatever, Wort gives you a way to recur at least part of them.
In addition, with Wort in play, having Gempalm Incinerator in your hand means you can pay 2 mana each turn to draw a card and, provided you have enough goblins on the battlefield, to uncounterably kill some creature in the process.

> Card Analysis

TODO

> Notable Exclusions

> Sensei's Divining Top

This is probably the first deck I've made without the Top.
It's still a good card, mind you, but I feel it doesn't bring enough to the cause. I just prefer to use the slot for other stuff.
Say you start by casting Sensei's Divining Top, the next turn you're rather willing to cast Grenzo, Dungeon Warden.
Yeah, you could use it on turn 3, provided you have spare mana for it, but the more the game advances, the less it matters what's in your hand and, as a consequence, what's on top of your library.
In the end, you're not going to activating it that much and, if you draw it in late game, it's mostly a dead card.

> Worldgorger Dragon

In the article that inspired this deck, they indeed recommended Worldgorger Dragon as a way to go off without having Grenzo on the battlefield.
At the beginning, I just thought the combo was too convoluted and I preferred to go for the more straightforward Mike & Trike.
As the time passed, I've come to build other decks with Worldgorger Dragon, but I never felt I might reintegrate it here.
In fact, Worldgorger combo is cheaper to deploy with Doomsday, but the point is: this deck is already on the "glass-cannon" category. It doesn't need yet another combo that loses you the game, should the opponent have - say - Swords to Plowshares.
Mike & Trike on the other hand, are cards that you can actually cast outside the combo and still get some value from them.

> Braid of Fire

This card seems an automatic inclusion, and indeed was in the deck at the beginning.
I soon realized it didn't fit in with the mana curve, so I removed it.
Let's say you cast Braid of Fire on turn 2 and then Grenzo on turn 3. By the time Grenzo hits the table, the first mana is already gone. Yeah, you get 2 more mana on turn 4, but you're only getting on par with your initial investment.
Ok, let's say you cast Grenzo first, then. On turn 3 you're not going to activate him, because you're busy casting Braid of Fire. On turn 4 you're only netting 1 mana, which is half a Grenzo's activation. Even worse.
At the end of the day, Braid of Fire is a card that does nothing for two turns, so it's out.

> Junktroller/Canal Dredger/Epitaph Golem

Nearly every other decklist I've seen runs a combination of these three cards. I don't understand why.
First of all, there has to be some creature in your graveyard, which won't necessarily be the case. Even if so, it's likely to be either because it was too big to be flipped by Grenzo, or it has somehow got killed.
If it was too big then, it's probably still too big now, so you have to find a way to pump Grenzo first, for this to work.
If was killed, tipically it was because of a board wipe, so Junktroller and friend are probably in your graveyard too. To me it's unlikely that it got hitted by a spot removal (they're likely to remove Grenzo instead).
I only see these cards worth getting value out of a creature that you sacrifice to Ashnod's Altar, or chump-block with each turn. But Ashnod's Altar is 1 card out of 99, you couldn't rely on that, and if you're forced to chump-block each turn, chances are you're kind of losing. I don't see you going anywhere with it anyway.
Epitaph Golem is slightly better because it doesn't tap to activate, so it can go infinite with Ashnod's Altar and a token-maker. The problem is: it has power 3, making it not that easy to flip with Grenzo. So it's out too.

> Soldevi Digger/Reito Lantern

These two were originally in the deck because, unlike Junktroller and friends, they can survive a board wipe.
In addition, they both can go infinite with Ashnod's Altar and any creature that makes 2 or more tokens. If the token-maker is also a sac outlet (like for instance Sling-Gang Lieutenant), you can swap the Altar for Mana Echoes and get the same result.
After all it's a nice combo to have, but the problem is: if you don't get either Ashnod's Altar or Mana Echoes into play, the other cards are quite unimpressive. And if I had Demonic Tutor in my hand, I'd rather go for Doomsday than waste my time going wide with tokens.
After some testing, I cut Soldevi Digger for being too narrow, since you can't chose the card to put on the bottom, but I kept Reito Lantern because it could act a a graveyard hate, since it can hit your opponents too.
As the time passed, I was consistently finding myself with better things to do with those 3 mana. In the end, by the time the card becomes relevant, the game is in its late stages and the deck isn't likely to survive anyway. So I cut it too.

> Tel-Jilad Stylus

With Grenzo out, this card can recur any of your creatures for value, although the ones that you actually may be interested in are only a few (I'm thinking about Dockside Extortionist, Goblin Matron, Imperial Recruiter, Priest of Gix, Tuktuk Scrapper and maybe Mindclaw Shaman).
All in all it's a neat trick, although it's unlikely that you get to pull it off. Otherwise, it's a 1-mana artifact that does absolutely nothing.

> Siege-Gang Commander and other token-makers

TODO

> Dimir Machinations

TODO