Okay, once again a more casual list, but I think there’s a seed of something here.

[deck]
[creatures]
4 Zurgo Bellstriker
3 Lightning Berserker
4 Mardu Scout
2 Tymaret, the Murder King
3 Vaultbreaker
1 Goblin Heelcutter
4 Goblin Rabblemaster
3 Mardu Strike Leader
4 Purphoros, God of the Forge
[/creatures]
[spells]
1 Hammer of Purphoros
4 Hordeling Outburst
4 Dragon Fodder
[/spells]
[lands]
4 Temple of Malice
4 Bloodfell Caves
4 Bloodstained Mire
2 Mana Confluence
2 Swamp
7 Mountain
[/lands]
[/deck]

There’s plenty of other options. If you want to go more black, both [card]Mardu Shadowspear[/card] and [card]Bloodsoaked Champion[/card] would be great. However, its better to just splash one of the colors. This could work even better as a purely red list:

[deck]
[creatures]
4 Zurgo Bellstriker
4 Lightning Berserker
4 Mardu Scout
4 Vaultbreaker
4 Goblin Heelcutter
4 Goblin Rabblemaster
4 Purphoros, God of the Forge
[/creatures]
[spells]
1 Hammer of Purphoros
4 Dragon Fodder
4 Hordeling Outburst
[/spells]
[lands]
23 Mountain
[/lands]
[/deck]

Or with white:

[deck]
[creatures]
4 Goblin Rabblemaster
4 Brimaz, King of Oreskos
4 Purphoros, God of the Forge
4 Vaultbreaker
2 Monastery Mentor
[/creatures]
[spells]
4 Raise the Alarm
4 Hordeling Outburst
4 Dragon Fodder
4 Secure the Wastes
2 Hammer of Purphoros
[/spells]
[lands]
4 Temple of Triumph
4 Battlefield Forge
2 Mana Confluence
4 Wind-Scarred Crag
6 Mountain
4 Plains
[/lands]
[/deck]

I think the [card]Vaultbreaker[/card] in each of these lists is a key card, because it can help dig for the Purphoros, without which the decks are just trying to go wide.