Engineered Explosives: A great card when you need to board wipe some creatures away. Can be cast for 1/2/3 and can be just be held up until needed.
Ancient Grudge: For the affinity matchup. If we mill it with Thought Scour, we can Flashback the spell. Also bring it in against Eggs/KCI Combo. Hard matchup with this one but it is better than most of the cards in our mainboard for it.
Destructive Revelry: Same as Ancient Grudge. However I have more of this because Enchantments are more of a nuisance to deal with. A lot of people in White will bring Rest in Peace against us. The 2 damage is also a nice bonus.
Blood Moon: Can literally lock some decks out of the game like Jund or Death's Shadow decks. Works well against Tron, but going late game, the can get around it if they keep hitting land drops.
Huntmaster of the Fells
:AMAZING CREATURE! Gets around Abrupt Decay and is very hard to deal with a lot of the time. Great for the midrange matchup.
Dispel: For counter wars or to push a spell through. Also allows you to leave up a single mana and counter something relevant possibly.
Surgical Extraction: Provides Graveyard hate at Instant speed for decks like Dredge and even just cards that can punish us such as Lingering Souls.
Relic of Progenitus: Bring in where our opponent is heavy graveyard like Dredge or a mirror. Also cantrips for us.
Pyroclasm: Quick board wipe for Burn, Tokens or Collected Company decks.