Cards like Atraxa, Grand Unifier, Tarmogoyf, Reconstruct History, and Nethergoyf increase in effectiveness the more card types you have access to, so including a few sorceries helps unlock these cards fullest potentials
Sphinx of Forgotten Lore $12.95 This sphinx has a lot of potential homes, but its mostly spellslingers and flash-matters
In a deck that can go wide on the board, as Knights certainly can, this ability is incredibly dangerous, and can easily finish an opponent off in conjunction with other board-buff effects such as History of Benalia
If you don't sacrifice a Forest, sacrifice this creature and it deals 7 damage to you
It also makes two additional Faeries when it enters the battlefield
Great in pods where you know people tend to not politic a lot or want to storm off or build stack-wars early on