Have you ever wanted to spend 10 turns durdling, then making a 30/30 and immediately throw it at your opponent's face? Then a Serpentine Curve deck may be for you! This build goes Grixis to give us all the options we could ever want and has a fun surprise for our opponent post-board -- but I'll be getting to that in a moment.
Without further ado, let's go into the card choices.
Take me out to the ball game, take me out with the crowd!
Wincon
For those who are not familiar, Curve decks work by filling up your graveyard with cheap spells, drawing into a copy of Serpentine Curve and Fling, and then dropping + Fling'ing your token to insta-kill your opponent. Big beaters on their own aren't good enough in Pauper what with all the removal flying around, so being able to win around removal is really what makes the deck viable.
However, that's not our only hope for victory. Fruit of Tizerus is a surprisingly good backup wincon While you generally want everything in this kind of deck to either interact or draw cards, there's enough room for one copy of this little gem to help us grind through slow matchups or matchups with a ton of countermagic. Countering our one-of Fling is disastrous but nobody can counter two Fruits a turn. Serpentine Curve counts cards in Exile as well as in the yard, so we don't have to distract from our main plan at all to give us some inevitability.
Buy me some peanuts and Cracker Jack
Card Advantage
Pauper is all about value engines and we run two: Cleansing Wildfire and Pieces of the Puzzle.
Wildfire is a big part of why this deck wants to be 3-colors, as it allows us access to enough of the indestructible lands that we can use it as a consistent form of ramp. The ramp is certainly nice but you can also think of this as draw-2-for-2 with upside, and either way we're very much into that.
Pieces is everything we want: not only does it draw us a lot of cards and give us great selection but it also stocks our graveyard very efficiently. If you're able to chain one Pieces into another, chances are good you'll be close to a lethal Curve.
Since Curve counts cards in exile, we can also run some Flashback fun-ofs for added value. Deep Analysis is ok to hardcast but it's magnificent when you bin it via Pieces and then flash it back for just 2 mana. Mystical Teachings doesn't grab every card we want but it's a great way to find critical countermagic or even our copy of Fling.
I don't care if I never get back
Card Selection
In addition to raw card draw, we also run some card selection to search for what we need when we need it while efficiently boosting Curve.
Preordain is an obvious inclusion. It just smooths out draws so very well.
Consider is our second cantrip, chosen mainly because it lets us bin spells we don't need. It's possible that Brainstorm would be better as we have plenty of shuffle effects, but that makes for risky keeps. Thought Scour is another contender but I would be concerned about accidentally milling Fling and leaving victory an extremely slim prospect.
We also have one copy of Flood of Recollection to recur key pieces on the cheap. Just two mana to get back your one copy of Fling, countermagic, a clutch removal spell, or even just a copy of Pieces comes in very handy.
Let me root, root, root for the home team
Lands
Not too much to say about the lands as there isn't room for too much spice. We have to run ten of the Grixis Bridges, favoring the blue bridges, to enable Cleansing Wildfire and Ash Barrens is our best backup color fixing, so we're left having to run basics for the rest. 20 may not seem like a lot given that our combo requires at least 6 mana to execute and we'll often want to leave countermagic up, but between Wildfire and just our high card draw, we don't usually have any trouble getting there.
If they don't win, it's a shame
Disruption
Our opponent isn't just going to let us kill them without fighting back, so we have a bit of hand and stack interaction to force our plan through.
Counterspell is our one-stop shop for maindeck counters. You know it, you love it, it slices and dices and even makes hotdogs and fries!
We also run two copies of Duress maindeck and it is sneakily good in Pauper. Almost every deck runs key noncreature spells and Duress can really punch a hole in their plan. It evades both Pyroblast and Hydroblast, either takes or forces a counterspell, and perhaps most importantly, it gives us a peek at our opponent's hand to check whether we're clear to go for the combo.
For it's one, two, three strikes, you're out
Removal
It takes a while to stock our yard, so we're gonna need to kill our opponent's dudes to stay alive long enough. Fortunately, Red and Black are exceedingly good at that.
Lightning Bolt is the OG Red kill spell and its power helps buoy our jank to victory. Going face is also a very real consideration since 3 damage dealt to our opponent means 3 fewer spells we need to get into the yard. Firebolt is another fun-of Flashback card, allowing us to kill two small creatures or dome our opponent for 4 over the course of the game. Finally, Fiery Cannonade isn't always what we need but it saves our bacon often enough in this format that maindecking one is worth it.
As for Black, it brings Cast Down and Chainer's Edict to the party. 2 mana to kill something big is exactly what we're in the market for.
At the old ball game!
Sideboard
The sideboard is mostly straightforward: Blue Elemental Blast, Red Elemental Blast, and Dispel to tailor our countermagic suite; Chainer's Edict, Fiery Cannonade, and Duress to double-down on removal already in the deck; Smash to Smithereens for Affinity; and a Nihil Spellbomb so we're not totally helpless to graveyard decks.
However, in matchups heavy on removal or countermagic where we might struggle to pull off our basically-Sorcery-speed-combo, we can board the combo out entirely and instead go with a beatdown plan courtesy of Goblin Wizardry. We can cast this on our opponent's end step after they tapped out and then swing with two 4/4s or even 5/5s+. Combine them with our existing burn and we have an entirely different vector of attack that our opponent was almost certainly not expecting.
Anyway, that's the deck. How do you like it? I'd love to hear your thoughts!