On arrival to the battlefield, it will counter any instant, sorcery or ability
When a small village is attacked by a group of Mukotai Reckoners, Chishiro finds a glimmer of comradeship from his old life and chooses to battle alongside them, leading them to a hard-won victory
Or is this a bigger format where it will birth a Volcanic Island
Card not found is sometimes seen in various sacrfice decks (or more colloqually, Cat-Oven decks), Evelyn is often the top end of vampire decks and Card not found sees some amount of play in Modern, but not really in other formats, weirdly enough
Of course, there isn't anything wrong with doing that, but you can draw more cards the other way
In addition to letting you cheat on expensive Equip costs, there are also some other sweet things that Sokka and Suki enable