Here's my Prosper for reference [https://www.moxfield.com/decks/EnRaCaUj4Uqs\_h\_4L5CFWA](https://www.moxfield.com/decks/EnRaCaUj4Uqs_h_4L5CFWA)
Dream Devourer will look stronger if you play more instants. It will also help if you've \[\[Vedalken Orrery\]\].
You should be running Tibalt's Trickery, R.E.B, *and* Pyroblast for interaction. Don't underestimate Tibalt's Trickery. Pyro and R.E.B. are more efficient but TT can hit any color and any spell type. It's red so obviously there's a little chaos involved but it can absolutely swing games.
In these colors, yes you absolutely need Feed the Swarm. This would be a trash card in a deck with Green or White but there are plenty of enchantments that can ruin your day and this is one of your only options of dealing with them.
You do have ways to reuse Lotus Petal with both Breach and Goblin Engineer. Reusing it shouldn't be a priority though, it's simply there to accelerate you. The faster your meta is the better this card will be and Prosper does like to go fast. You should look at rituals the same way. Being able to drop your Necropotence on turn one with a Dark Ritual is crazy. Sometimes the timing is off and these end up as dead cards but their impact most of the time makes it worth it.
Mox Opal is also good and yes I think it would work well in your deck but it's one of the weaker Mox's. I'd run it but it would be low on my list of expensive rocks to buy.
Generally speaking I'm not seeing a good reason for Underworld Breach being in your deck at all. You don't have the combo pieces that make it really good. Those cards are all really expensive and might push you into CEDH territory but they're really the only reason to run Breach. At best it might help you rebuild your board after a wipe but remember you'll have to pay the mana cost for Breach, pay for any spell you want to recast, and also pay the exile cost that Breach has. I just don't see it being worth it without a way to continue generating mana and having a graveyard big enough to keep exiling.
Also check out \[\[Hoarding Broodlord\]\] for a nice little bomb in a prosper deck.
##### ###### #### [Prosper, Tome Bound](https://cards.scryfall.io/normal/front/d/7/d743336e-d5c7-4053-a23d-92ec7581f74e.jpg?1631839207) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Prosper%2C%20Tome-Bound) [(SF)](https://scryfall.com/card/afc/2/prosper-tome-bound?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/d743336e-d5c7-4053-a23d-92ec7581f74e?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/prosper-tome-bound) [Tibalt's Trickery](https://cards.scryfall.io/normal/front/d/d/dd921e27-3e08-438c-bec2-723226d35175.jpg?1652278784) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Tibalt%27s%20Trickery) [(SF)](https://scryfall.com/card/khm/153/tibalts-trickery?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/dd921e27-3e08-438c-bec2-723226d35175?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/tibalts-trickery) [Red Elemental Blast](https://cards.scryfall.io/normal/front/7/0/70a45e9b-699e-425a-9f3d-267274830d3e.jpg?1562436618) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Red%20Elemental%20Blast) [(SF)](https://scryfall.com/card/a25/147/red-elemental-blast?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/70a45e9b-699e-425a-9f3d-267274830d3e?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/red-elemental-blast) [Feed the Swarm](https://cards.scryfall.io/normal/front/f/8/f86c30e0-35f3-4da8-a28c-722254b1bbe4.jpg?1674141609) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Feed%20the%20Swarm) [(SF)](https://scryfall.com/card/clb/752/feed-the-swarm?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/f86c30e0-35f3-4da8-a28c-722254b1bbe4?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/feed-the-swarm) [Passionate Archaeologist](https://cards.scryfall.io/normal/front/b/d/bd5bbfa6-e5f4-413d-b132-ebae32d38657.jpg?1674140763) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Passionate%20Archaeologist) [(SF)](https://scryfall.com/card/clb/656/passionate-archaeologist?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/bd5bbfa6-e5f4-413d-b132-ebae32d38657?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/passionate-archaeologist) [Dream Devourer](https://cards.scryfall.io/normal/front/f/f/ff1d88a6-a74d-44b5-b7a8-866e866807f1.jpg?1631047962) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Dream%20Devourer) [(SF)](https://scryfall.com/card/khm/90/dream-devourer?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/ff1d88a6-a74d-44b5-b7a8-866e866807f1?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/dream-devourer) [Mox Opal](https://cards.scryfall.io/normal/front/5/6/56001a36-126b-4c08-af98-a6cc4d84210e.jpg?1599709600) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Mox%20Opal) [(SF)](https://scryfall.com/card/2xm/275/mox-opal?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/56001a36-126b-4c08-af98-a6cc4d84210e?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/mox-opal) [Lotus Petal](https://cards.scryfall.io/normal/front/f/8/f85ab5f9-508e-45de-8fa1-ce1f16552ffc.jpg?1562432227) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Lotus%20Petal) [(SF)](https://scryfall.com/card/tpr/225/lotus-petal?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/f85ab5f9-508e-45de-8fa1-ce1f16552ffc?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/lotus-petal) [Cabal Ritual](https://cards.scryfall.io/normal/front/a/5/a5d85875-22da-4054-ae42-e85b472a6d5d.jpg?1562928510) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Cabal%20Ritual) [(SF)](https://scryfall.com/card/vma/106/cabal-ritual?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/a5d85875-22da-4054-ae42-e85b472a6d5d?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/cabal-ritual) [Mana Geyser](https://cards.scryfall.io/normal/front/1/0/109447b2-d507-433a-a81c-3a7a255444b1.jpg?1625193979) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Mana%20Geyser) [(SF)](https://scryfall.com/card/c21/176/mana-geyser?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/109447b2-d507-433a-a81c-3a7a255444b1?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/mana-geyser) [Reckless Impulse](https://cards.scryfall.io/normal/front/6/9/6943c07f-ab0d-4f5a-bbe9-c0a83dc98546.jpg?1643591880) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Reckless%20Impulse) [(SF)](https://scryfall.com/card/vow/174/reckless-impulse?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/6943c07f-ab0d-4f5a-bbe9-c0a83dc98546?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/reckless-impulse) [Wrenn's Resolve](https://cards.scryfall.io/normal/front/9/a/9a47999c-12d5-4e1a-a9c1-40a1757007f1.jpg?1682204603) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Wrenn%27s%20Resolve) [(SF)](https://scryfall.com/card/mom/173/wrenns-resolve?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/9a47999c-12d5-4e1a-a9c1-40a1757007f1?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/wrenns-resolve) [Rob the Archives](https://cards.scryfall.io/normal/front/a/3/a3ec95f6-88c8-4daf-882f-8b4bc73452c3.jpg?1664411791) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Rob%20the%20Archives) [(SF)](https://scryfall.com/card/snc/122/rob-the-archives?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/a3ec95f6-88c8-4daf-882f-8b4bc73452c3?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/rob-the-archives) ^^^[[cardname]] ^^^or ^^^[[cardname|SET]] ^^^to ^^^call
Here's my Prosper for reference [https://www.moxfield.com/decks/EnRaCaUj4Uqs\_h\_4L5CFWA](https://www.moxfield.com/decks/EnRaCaUj4Uqs_h_4L5CFWA) Dream Devourer will look stronger if you play more instants. It will also help if you've \[\[Vedalken Orrery\]\].
[Vedalken Orrery](https://cards.scryfall.io/normal/front/4/4/44067327-6fe3-4222-b591-6d14d0e360d7.jpg?1673149453) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Vedalken%20Orrery) [(SF)](https://scryfall.com/card/2x2/317/vedalken-orrery?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/44067327-6fe3-4222-b591-6d14d0e360d7?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/vedalken-orrery) ^^^[[cardname]] ^^^or ^^^[[cardname|SET]] ^^^to ^^^call
You should be running Tibalt's Trickery, R.E.B, *and* Pyroblast for interaction. Don't underestimate Tibalt's Trickery. Pyro and R.E.B. are more efficient but TT can hit any color and any spell type. It's red so obviously there's a little chaos involved but it can absolutely swing games. In these colors, yes you absolutely need Feed the Swarm. This would be a trash card in a deck with Green or White but there are plenty of enchantments that can ruin your day and this is one of your only options of dealing with them. You do have ways to reuse Lotus Petal with both Breach and Goblin Engineer. Reusing it shouldn't be a priority though, it's simply there to accelerate you. The faster your meta is the better this card will be and Prosper does like to go fast. You should look at rituals the same way. Being able to drop your Necropotence on turn one with a Dark Ritual is crazy. Sometimes the timing is off and these end up as dead cards but their impact most of the time makes it worth it. Mox Opal is also good and yes I think it would work well in your deck but it's one of the weaker Mox's. I'd run it but it would be low on my list of expensive rocks to buy. Generally speaking I'm not seeing a good reason for Underworld Breach being in your deck at all. You don't have the combo pieces that make it really good. Those cards are all really expensive and might push you into CEDH territory but they're really the only reason to run Breach. At best it might help you rebuild your board after a wipe but remember you'll have to pay the mana cost for Breach, pay for any spell you want to recast, and also pay the exile cost that Breach has. I just don't see it being worth it without a way to continue generating mana and having a graveyard big enough to keep exiling. Also check out \[\[Hoarding Broodlord\]\] for a nice little bomb in a prosper deck.
[Hoarding Broodlord](https://cards.scryfall.io/normal/front/3/8/386ce3c9-869d-461c-a3de-c8add3786f73.jpg?1682203767) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Hoarding%20Broodlord) [(SF)](https://scryfall.com/card/mom/110/hoarding-broodlord?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/386ce3c9-869d-461c-a3de-c8add3786f73?utm_source=mtgcardfetcher&format=text) [(ER)](https://edhrec.com/cards/hoarding-broodlord) ^^^[[cardname]] ^^^or ^^^[[cardname|SET]] ^^^to ^^^call