My original build of this deck was a much less combo focused so I have a couple recommendations. Some of these are pretty meta dependent/ maybe not that great.
Netherborn Phalanx - If people are flooding the board with creatures/tokens in your meta this can just one shot people. Obviously not a great early flip.
Anathemancer - Similar to Phalanx but for non-basic lands.
Guiltfeeder - Can hit for a lot late game and comes with some evasion.
If you want to flip some large creatures Ignition Team and Nighthowler tend to be quite large.
If you're on the go wide plan yourself, Purphoros, God of the Forge and Ogre Battledriver seem good.
Similarly, Archetype of Finality makes your go wide strategy hard to attack into/block and combos well with Goblin Sharpshooter and similar cards.
Another random suggestion Soulbright Flamekin can turn 6 mna into 8 mana and give your creatures trample in the process.
Hopefully one of those random suggestions was helpful.