Nightmare Moon / Princess Luna It takes 6 mana to transform Nightmare Moon the same way it took the six Elements of Harmony wielded by Twilight Sparkle, Rarity, Applejack, Fluttershy, Pinkie Pie, and Rainbow Dash to do so in the show
Its about 75% committed to being an otter deck (why are there three copies of Waterspout Warden here?), and the rares arent half-bad, with the exclusive Bria, Riptide Rogue being an actual house of a card
Falkenrath Aristocrat : Two generic, one black and one red mana, 4/1 Vampire, flying, haste
Cards that reduce the cost of other spells can also easily lead to combo situations
Instead, look at Narnam Renegade, Gnarlwood Dryad, Wasteland Viper, and Venerated Rotpriest
But I couldn't get on with them, or they left me cold