There are multiple ways to go about building a Rakdos deck. You could go monored with a slight splash of black, it might be better than a pure monored deck but we cannot call it a true Rakdos deck if it is only a splash. I tried to make a more midrange deck with Angrath, the Flame-Chained, while it might be a fun build I think it will be one of the weaker midrange decks. While making a tier1 deck is not the goal I would prefer a deck that I do not consider dead out of the gates. Another approach is going the burn or discard route, very tempting but what caught my attention was a Rakdos Pirates deck from /r/spikes by user PapaLoki.This deck is built with BO3 in mind.

The New Pirate Lord

With pirates, we have access to a lot of low-curve aggressive creatures and we also get a pirate lord now with Judith, the Scourge Diva. This deck makes it very easy to curve out with creatures and get that extra reach by finishing off with burn spells. You can refill your hand with cards like Rix Maadi Reveler and Ruin Raider, there is also The Flame of Keld for refilling and extra reach.

You might remember this card back at the beginning of MTGA beta when Monored pirates were a thing. Well, she is back and with 20 Pirates in the deck her coming down at a discount is even more likely now than last time. Having 2 toughness is also key against cards like Chainwhirler.

Against mono-red you have to be careful and not commit too many of these on the board in respect Chainwhirler. You do not want to lose multiple cards to that guy so be very careful with overcommitting against mono-red and try to get out some 2 toughness creatures. While Judith, the Scourge Diva acts as the pirate lord in this deck, she does not offer any additional protection. 

You want to play this card for its spectacle cost to refill your hand. A very powerful tool giving us access to the extra reach for finishing off resilient opponents. While this guy is mainly for refilling, it can also fix your hand and help you curve out, making it good as a 2-drop too.

Another card refiller, not very excited for a 3 cost card but a 3/2 body with card draw and pirate synergy makes it worth having 2 of them in the deck. Remember that you can play this after you have attacked and get the effect of the card!

There are only 6 cards in this deck that does not trigger this card, Grasping Scoundrel and Ruin Raider. Also with our highest CMC in the deck being only 3 we till be out of cards quick and this is perfect for refilling and also giving us extra damage for the reach.

A forgotten card that is very useful in a tribal deck with this. Instead of 8 dual land sources, you now have access to 12!

Other useful cards to take a look at:

While I am not a big fan of combat tricks in constructed, not many people play around cards like this and it might be reasonable to replace a Skewer the Critics or two with it.

Sideboard:

Vs Aggro
Replace Skewer the Critics with Fiery Cannonade for a potential one-sided boardwipe.

Vs Midrange
Out with Skewer the Critics and in with Lava Coil

VS Control
Remove Skewer the Critics and Dire Fleet Captain, replace with Kitesail Freebooter and Duress.