Why BR storm > UR storm
1) This variant is more explosive. You only need one engine - waste not or pyromancer ascension - to combo off; whereas UR has difficulty without ascension.
2) Rakdos storm vs any blue deck is an easy matchup. Blue decks like to hold onto cards, which makes dark deal more powerful. Burning Inquiry is also great against scry heavy decks.
3) Burning Inquiry hurts them more than it hurts us, because we like having things in our graveyard.
4) Chaining spells together becomes more meaningful because your spells interact with each other (also a con).
5) BR storm plays better against combo hate and junk. We like to put cards in our graveyard.
6) Waste Not is less susceptible to removal (compared to Goblin Electromancer).
7) In my opinion, BR storm has a stronger sideboard game.
Why UR storm > BR storm
1) UR is more consistent. If you want to be successful with Rakdos storm, you NEED to be able to crunch a lot of numbers e.g. using Bayes Theorem to solve the probability of drawing and keeping a Dream Salvage with a Burning Inquiry. Even then, there's the chance that everything goes wrong. (Also a pro since BR is more likely to win on turn 3).
2) The spells in this list are rarely useful by themselves. Burning Inquiry and Dark Deal are underwhelming without a waste not/dream salvage and vice versa. Opponents can use this to their advantage.
3) Rakdos storm is harder to play, and it's easy to make mistakes.
4) Graveyard hate really hurts.
5) Dark Deal is next to useless against decks that dump their hands early i.e. affinity
6) Sideboarding for BR storm could potentially be ineffective. There's a significant probability of discarding your sideboard cards (this is why Ancient Grudge > Shatterstorm/Shattering Spree/Wear+Tear)
I'd appreciate advice on this deck. Here are my thoughts so far:
Ascension is underwhelming, and it's only really useful vs blue decks, where we have an easy match up already. I might try taking out Ascension and Manamorphose for Pentad prism and a playset of another card. Maybe I'd need to replace faithless looting too?
Cards to consider, which I've yet to try:
Pentad Prism,
Night's Whisper,
Read the Bones,
Plunge into Darkness,
Chromatic Star,
Tasigur's Cruelty.
Beseech the Queen,
Ad Nauseum,
Infernal Plunge,
Infernal Tutor.
I might also try running a different mana base. Three polluted deltas, one wooded foothill; three swamps, one mountain; and overgrown tomb in the sideboard.
Mainboard cards that I've tried and was unimpressed with:
Simian Spirit Guide,
Locket of Yesterdays,
Reforge the Soul,
Tormenting Voice,
Duress/Thoughtseize/Inquisition of Kozilek mainboard (although it might be worth trying again if I take out Ascension).
Sideboard cards to try:
Dismember,
Terminate,
Dreadbore,
Thoughtseize,
Blood Moon.
Sideboard cards I've tried:
Abrupt Decay,
Choke,
Boseiju Who Shelters All,
Gutteral Response,
Surgical Etraction,
Lightning Bolt
This list was inspired by Gathering Magic
https://www.youtube.com/watch?v=4ejSGruhPS8