There aren't any, and there won't be any.
Players get priority during the draw step after the draw. This means that instant speed discard has the ability to rob a player of the ability to play their sorcery speed cards before they ever get the opportunity to play them.
As a consequence, Wizards really hates printing instant speed discard, and hates repeatable instant speed discard even more so. There's enough ways to deal damage at instant speed to make a card like the one you want to qualify as repeatable instant speed discard, so they aren't going to print it in the foreseeable future.
Furthermore, the Underworld Dreams effect has been printed several times, and is powerful enough that people have built competitive decks around it even without adding a loop to the deck.
Discard and land destruction are two of the most closely monitored deck strategies, because Wizards thinks that being unable to play your spells is the least fun position to be in, and players who aren't having fun tend to stop buying cards.