Goal
I built this deck with the goal of having fun with Prosper as a commander. It has a lot of impulse draw and typical cast-from-exile shenanigans, but is aimed more at accomplishing something on your own that isn't relying on stealing cards from the opponents' decks or comboing off.
While there are various cards that would help this deck be "more powerful and efficient," the goal of this deck is to be strong on its own without being overwhelming. My current playgroup is newer players with more grindy decks that ultimately win on the ground, even if they do have combos to get them there. Therefore, this deck is intended to pack removal and be able to withstand removal from other players. Prosper is treated as a value engine... a means of generating card advantage and ramp. The rest of the deck is built to hopefully run with or without him. Instead of wincons like Revel in Riches or combo pieces like Marionette Master, I opted for more board presence and even recursion.
Impulse Draw
Since you are probably familiar with the concept of exiling cards from your library to cast them, especially if you are looking at a Prosper deck, I'll concentrate on what I feel sets my deck apart. On to the important parts!
Discard?
One of the issues I've had with my Prosper deck since I started playing with it is the condition of cards piling up in hand when I favor playing cards from exile. Often, I will choose to play the land from exile instead of one from my hand, because it will net me the land plus a treasure token from Prosper... effectively netting me two mana for the turn's land drop. This would cause lands to build up in hand along with other cards. I found these cards would be stuck there while I was trying to generate treasure tokens. That's when I started to add some cards that benefitted the theme while allowing me to use the cards in hand in a more efficient manner.
Chainer, Nightmare Adept allows me to discard a card and recur a creature from my graveyard. Plus, gives haste not only to recurred creatures, but to creatures cast from exile as well!
Malfegor offers the ability to discard your hand in order to force your opponents to sacrifice creatures.
Magmatic Channeler and Harnfel, Horn of Bounty (the flip side of Birgi, God of Storytelling
) allow you to exchange cards in hand for the ability to exile cards from the top of your library and trigger Prosper's abilities.
Throes of Chaos can help fill this role as well, allowing you to discard a land card and cast it from your graveyard.
Overall, adding this handful of cards to enable a minor amount of discard has felt like it helped streamline my build. I highly recommend it if you are seeing cards build up in your hand while playing this commander as well.
Board Presence and Removal
With this deck's emphasis on having a bit more of a board presence, I aimed to have two additions: big bodies and mass removal. I tried to integrate these two together as much as possible for the sake of having decent efficiency. After all, both of these categories usually come with a hefty mana cost.
The first creature that fulfills the big body role is actually a small guy. Kalain, Reclusive Painter is an enabler that allows all of my creatures to come down with some extra heft. Adding +1/+1 counters to each creature for each mana from a treasure used to cast them enables even the smallest of my creatures to come in with some beef. Tossing treasure for Balefire Dragon to potentially come in as a 13/13 flyer is just pure carnage.
Balefire Dragon and Malfegor are large creatures that also act as removal and can even be one-sided wrath effects on a body. Wipe the board while you are beating face!
Etali, Primal Storm is a no brainer for the Prosper deck. His big body and cast-from-exile effect fuels everything this deck wants to do.
Moving on to the mass removal. I opted to concentrate on one-sided board wipes. Prosper likes to have his board intact to keep churning out that value, so keeping the carnage to your opponents side of the board is paramount.
Plague Wind is the premier one sided wipe in this shell (I see very few planeswalkers in my meta, if you see them more often, I recommend In Garruk's Wake). It's high cost of nine (9) mana is usually overcome by Propser's treasure generation. Plus its high cost can work in concert with another one-sided removal spell, Volcanic Vision. Volcanic Vision allows you to bring back an important instant or sorcery spell and deal damage equal to that spell's mana value to each creature your opponents control. Perfect for bringing back Plague Wind or Fevered Suspicion!
Along with the aforementioned Balefire Dragon and Malfegor, the one-sided board-wipe suite is rounded out by Volcanic Torrent, which can be devastating when cast while Prosper is pumping out spells.
Conclusion
Overall, I like this build of Prosper. It's more casual than some, but absolutely brutal. I took out Sire Of Insanity and Possibility Storm as they were a bit much for my meta, but I would probably play them in other circumstances. Hopefully this proves to be an interesting take on Prosper for others as well.
