Its cheap and, most importantly, nearly impossible to remove without a board wipe or edict
There have been instances where Mono-Black Control, or Orzhov Control, has been at the top of the metagame
With the release of Tarkir: Dragonstorm , we're witnessing a new golden age - where graveyards fuel zombie-spawn engines, more ETBs cheat winged monsters into play, and toughness-based triggers can decimate pods in a single turn
Pako hits the field running with haste for 5 mana and can get up to a 7/7 after its first attack trigger
Ive heard the resulting process described as degenerate gambling before, though thats obviously on the buyers end more than the seller
You are bound by some rules and regs, though