(T: Add B or R to your mana pool.)
Canyon Slough enters the battlefield tapped.
Cycling 2 (2, Discard this card: Draw a card.)
Quote from Aethenlor »Black has the second best card draw in the game, we just have to pay life for it. While Necropotence isn't exactly card draw, it's the best way to get cards into your hand, and you have things like sign in blood and read the bones, night's whisper and necrologia. I had a black commander deck that could reliably get my deck in my hand each game. Green is much worse at card draw than black, although it does have some contenders with harmonize and the effects where you draw equal to a creature's power or the number of lands you control. But yeah, RB is a fun combination.
Oh, and red gets card draw with loot style effects, like faithless looting, cathartic reunion, and desperate ravings. White is bad at it, but you have the enchantress cards and things like Sram, senior edificer.