First, the number of individual cards
Id only avoid this if I had a fairly low curve and just wanted to attack with cheap creatures, as its ultimately just another mana source if the game goes long enough
Additionally, five mana is kind of pricy, and Sunfall is still around to ruin our fun
10 Knight Of The Ebon Legion This particular one-mana Knight was a key player in black aggro and midrange strategies during its tenure in Standard, and still sees play in Pioneer and Explorer
Some of these are asymmetrical or leave you ahead on board, like Ruinous Ultimatum and Martial Coup, but you'll have to be a bit more diligent with the others
BPhillipYork: It's kind of neat because it's cheap and just sits there, you know you'll cast your Commander at some point, or it's to super power something you're cheating out