In a wedge format, lots of people will be playing their most expensive three color cards, which means people often have a glut of expensive cards. The removal in this format isn't super cheap either, so you can take serious advantage of all that by being the guy with Bloodsoaked Champion.
Black has several under-utilized aggressive cards in Brain Maggot, Tymaret, the Murder King, and the aforementioned Bloodsoaked Champion. Additionally, these cards all play well with what Mardu is trying to do, so it seems like win-win. Butcher of the Horde wants another good creature to sacrifice, and Goblin Rabblemaster is great for triggering raid and turning on Tymaret, allowing you to go long in attrition-based matchups.
The one downfall of trying to be aggressive in a three-color deck is the manabase. Azren has only eight lands that enter the battlefield tapped, which I think is a good number. Still, they have the potential to slow him down, and if he doesn't draw any of them, he runs the risk of having a very painful manabase thanks to Caves of Koilos, Battlefield Forge, and Mana Confluence. Overall, I think there's a good balance here, but it's something to be aware of.
At the end of the day, what's more scary -- Elspeth, Sun's Champion or Bloodsoaked Champion? I think it's close, but if I've been preparing to fight Elspeth, Bloodsoaked Champion is likely going to be a problem.
- 4 Bloodsoaked Champion
- 4 Butcher of the Horde
- 4 Goblin Rabblemaster
- 2 Stormbreath Dragon
- 3 Brain Maggot
- 3 Tymaret, the Murder King