The Deck
Exactly as it says on the tin. This deck intends to take full advantage of Greven's abilities to try to kill everyone at the table with one punch. I've had to tinker with this deck a ton since, even though it has perhaps the highest kill count of any of my decks, I haven't won with it as much as I'd like. In particular, I've been focusing on lowering the ceiling on the mana curve. A lot of the cards that I had in this brew before seemed to sit in my hand for a long time and not do much. I think that if I can get Greven out sooner into an established board the deck has a much better chance to go the distance.
The Captain
Greven, Predator Captain is a powerhouse among voltron-style commanders. He's evasive, he generates card advantage, and he's very easy to pump up to instant-kill size with the right tools. The problem with Greven comes from the fact that he is a big, obvious threat. Getting him on the board and having him stick long enough to declare attackers is often the most challenging part of piloting the deck. The key pieces in this deck revolve around getting Greven out safely, suiting him up quickly, using pinpoint life loss to threaten a kill, and granting lifelink to get ready to do it all again.
The Mates
Timing Greven is one of the trickier things about piloting this deck. One cannot simply ramp into Greven and cast him into an empty board. If the pieces aren't in play for him to immediately be able to come in and start swinging then he is not only not very impactful but is also a sitting duck for removal. To the end of helping set up the board I have specifically added three creatures: Daretti, Scrap Savant, Goblin Engineer, and Goblin Welder. The plan is to use their effects in conjunction with a suite of useful artifacts to safely put Greven into play, suit him up, and get him ready to start swinging in for big damage against my opponents.
The Ramp
Part of the utility of the Goblin Welders is their ability to help move rocks around. All of the ramp in this deck are rocks and they are all between 1 and 3 cmc. Sol Ring is the best among these in terms of sheer ramp. The next best things are the untapped 2-drop rocks like Rakdos Signet, Mind Stone, Fellwar Stone, and Talisman of Indulgence. Finally, three drop rocks that tap for more than one such as Basalt Monolith, Coalition Relic, and Worn Powerstone are helpful for getting Greven out given his CMC of 5.
Furthermore, to help enable the welders I have ways to generate temporary artifact ramp through Captain Lannery Storm and Curse of Opulence.
In addition to the artifact ramp I also have big rituals in the form of Treasonous Ogre in red and K'rrik, Son of Yawgmoth and Dark Ritual in black. These effects can enable huge turns for the deck as they can not only help cast Greven but also serve as or enable pinpoint life loss to pump Greven up to instant-kill size. Since both of them are (effectively) 4-drops they work out great in the deck.
Card Draw and Tutors
Greven is the most powerful draw engine in the deck but he cannot work on his own. Part of the Goblin Welder package is a set of big artifact creatures that Greven can sacrifice to his attack trigger in order to generate tons of card advantage. Lupine Prototype and Phyrexian Soulgorger are among the highest power cards for their converted mana cost in the game and both can be cheated into play by the welders. Additionally Immolating Souleater has a phyrexian mana-costed half-firebreathing effect that makes it not only able to grow arbitrarily large in order to be sacrificed to Greven's trigger for a bunch of cards but can also easily pump up Greven to a size where he can kill in one hit. Additionally the welders can help get Key to the City into play. Not only can this help Greven to break through wide board states for free put it also provides a surprisingly useful slow rummage effect.
At the end of the day, any creature in the deck can provide card advantage when sacrificed to Greven's attack trigger but there are some other creatures of particular note in this category. Azra Oddsmaker works great in this deck as it rewards the deck's primary strategy with card advantage. Flamewake Phoenix, Rekindling Phoenix and Golgari Thug are creatures that can repeatedly recur themselves from the graveyard for incremental card advantage.
Greed and Phyrexian Reclamation are great enchantments for refilling the grip while Greven is offline and Daretti, Scrap Savant provides a repeatable Faithless Looting effect that is great for rummaging. Though not strictly card draw, Doom Whisperer is another strong utility in the deck as he not only enables pinpoint life loss for Greven but can also dump cards into the graveyard as many times as I like helping me to look for the cards I need. Likewise, Bolas's Citadel allows for the cheating of permanents and spells in exchange for life and provides a longshot alternate win cond in the event a Greven win becomes impossible.
The deck also runs a few tutors. In particular, I find Gamble and Scheming Symmetry to be useful.
Haste and Lifelink
The most important keywords to get on Greven are haste and lifelink. If he has haste, I don't have to wait a full turn of the table to start swinging with him and, if he has lifelink, no matter how much life I dump into pumping Greven up, I'll get it back after he connects. To the end of enabling these the Goblin Welders can specifically go find Shadowspear, Basilisk Collar, Swiftfoot Boots, Hammer of Purphoros, Obsidian Battle-Axe, and Whip of Erebos. Of these Shadowspear and Swiftfoot Boots are perhaps the best as the boots also give The Captain hexproof (a keyword that rakdos is sorely lacking) and the Shadowspear can do a decent impression of Bonds of Mortality which can be relevant for removing my opponents' threats. Hammer of Purphoros is nice because it does provide haste to all creatures I control and can generate me bodies to sacrifice to Greven or the Goblin Duo, but its dual typing makes it somewhat easier to remove than the others. Whip of Erebos doubles as a way to recur creatures from the graveyard to sacrifice to Greven or a one-time effect to bring Greven back with haste.
Chainer, Nightmare Adept came in the same precon and Greven and synergizes with him well. It grants him haste whenever he's cast from the command zone and provides a useful way to pitch cards to the yard and reanimate them. Also, Tentative Connection can act as a haste enabler for Greven in a pinch.
Protecting The Captain
Even before Greven hits the board he is an obvious threat. Part of the job of the Goblin Welders is to keep my opponents' strategies at bay and help ensure The Captain's safety as he enters the board and when he goes to attack. Part of the artifact suite of this deck are what I'd like to call the "fair stax" effects. These cards aren't the most optimized but help lock down dangerous strategies and help keep The Captain safe. They aren't the best versions of these effects but they do the job hopefully without drawing too much ire from my opponents and without putting a sizeable dent in my paycheck.
Torpor Orb: Aside from the ever-present spectre of Thassa's Oracle combos, this card specifically can help me get around Stonehorn Dignitary locks which can be a big threat to this deck.
Defense Grid: This one is key. Rakdos lacks access to effects like Insist so any ways that make it harder for my opponents to counter The Captain are immensely useful.
Silent Arbiter: This guy does double duty for the deck by not only making Greven effectively unblockable but also weakening my opponents' ability to crack back at me by limiting the number of creatures they can attack with per turn.
Veilstone Amulet: This is a very underappreciated card that can give can my board hexproof whenever I cast a spell.
In addition to the artifacts mentioned above the deck runs a variety of other protection effects. Imp's Mischief, Bolt Bend, and Not of This World counter or redirect single-target removal effects that get aimed at The Captain. Red Elemental Blast can also work against counterspells and bounce effects and doubles as a way to remove troublesome blue permanents. If all else fails, Fling allows Greven to go out on his own terms, going to the yard or command zone as I see fit and potentially taking someone down with him. Lastly, Daring Fiendbonder is a great sacrifice target for Greven that doubles as a cheap way to give Greven indestructible in a particularly hard to interact with way.
Removal and Board Wipes
The deck runs a small suite of flexible instant speed removal spells. I have specifically chosen Bedevil for artifacts, creatures or planeswalkers, Murderous Rider for creatures or planeswalkers while doubling as a warm body to sacrifice to Greven, Feed the Swarm for creatures and enchantments, and Chaos Warp for any type of problematic permanent. Lastly, the deck includes the incredibly efficient threaten effect of Tentative Connection in order to steal opponents' creatures only one red mana to sacrifice to Greven's trigger.
As far as board wipes, the deck runs effects like Phyrexian Purge and Fire Covenant as they double as ways to pump up Greven to massive size while also selectively removing troublesome creatures from the board. Chandra's Ignition is the most expensive board wipe in the deck, but it more than makes up for it by being able to potentially all of my opponents at once.
Power-Ups
Tainted Strike gives Greven infect allowing him to kill with only 10 power instead of 21. Temur Battle Rage makes him extra dangerous by providing double strike and trample and Embercleave does the same on an equipment that can be cheated in with Daretti or Goblin Welder. Additionally, Combat Celebrant and Seize the Day can provide additional combat steps for Greven that can help him finish off multiple opponents quickly.
Key to the City, Manifold Key, and card Rogue's Passage all help Greven to get through with damage by making him unblockable.
Recursion
The deck also runs a couple of good reanimation and recursion effects to get pieces back from the graveyard if they get destroyed. Animate Dead can bring back any creature from any graveyard for only two mana and Underworld Breach can allow me to recast any number of spells from my graveyard as a one-time effect. Phyrexian Reclamation is a cheap enchantment that can bring back creatures from my graveyard to my hand in exchange for life.
