It's a go-to sideboard card in artifact decks like Hammer Time or Tron, especially when you need answers but can't afford to play black mana
(Although I should note that we do push these decks to fringe levels every once in a blue moon.) Utility discard cards, on the other hand, do not necessarily promote the discard decks unto themselves (although they are used if enough resources for the discard deck exists)
These have been around since Dark Ascension and have cropped back up in almost every set featuring double-faced cards, but now theres a commander that wants you to put them all in the same deck
Here are your choices: [4] Buy packs or booster boxes and build a deck out of the cards you open
4 Kinbinding Kinbinding offers a huge infusion of power for your creatures, for as many creatures entered that turn
Prismatic Strands is a Pauper staple, effectively acting as two fog spells in one to help win aggressive races