KEY CARDS & INTERACTIONS:
Deathpact Angel & Sire of Insanity: These are both bomby, valuable creatures that are hard to deal with: Angel keeps coming, where Sire can't be taken out without a miraculous topdeck. Both beat face pretty hard.
Ember Swallower & Alms Beast: Our valuable 4-drops. Both clog the ground and are fat for their mana cost. If Ember Swallower manages to get monstruous active, he grows a lot and destroys the opponent manabase (yours too, but you are left with at least a 7/8 body). Both dodge damage based removal, and Alms Beast dodges Doom Blade.
High Priest of Penance: Tough blocker since turn 2, this can blow up permanents backed up by some removal.
Aurelia's Fury: If done in the opponent's upkeep, this can be pretty backbreaking: fog effect + silence is practically a timewalk. On top of it, it burns face and removes creatures.
Flames of the Firebrand, Magma Jet & Read the Bones: Our 2-for-1 cards.
Rakdos Keyrune & Haunted Plate Mail: Both dodge removal and sweepers and can defend fairly well. Keyrune also ramps, while Mail can be equipped, so they're never dead.

Non-budget options: Blood Baron of Vizkopa, Rakdos's Return, Chained to Rocks, Boros Reckoner, Stormbreath Dragon and the shock-check manabase.