Psychic Purge

A blue burn spell is the joke, but the second clause is the design. The damage half is a throwaway: one mana to ping for one is barely a Magic card on its own. The discard-punisher rider is what the slot is built around, and it taxes an opponent for trying to resolve their own strategy through you. In an era when Hymn to Tourach, The Rack, Mind Twist, and Hypnotic Specter were defining black's discard plan, Psychic Purge sat in hand as a five-life landmine: cast it for the ping when convenient, or hold it and dare the discard deck to make you pitch it. The asymmetry is the point. The opponent's own card is the trigger; you cannot fire the rider yourself, which is why the rate on the front half is so anemic. Wizards has revisited the "punish them for making you discard me" template a handful of times since (Megrim works the same logic from the other side, rewarding the controller for forcing discards rather than punishing the forcer), but Purge is the cleaner statement of the idea: a card that exists primarily as a threat while it sits in your hand, and only secondarily as a spell you actually cast.