How does the clean-up step work if I had to discard a card and had Archfiend of Ifnir and Generous Patron on the battlefield? Would I keep drawing and discarding until my opponents didn't have any creatures left?
Players don't get priority in the cleanup step unless an ability triggers because of something that happens in the cleanup step, such as Archfiend of Ifnir triggering. When something triggers in the cleanup step, that trigger will go on the stack and players will get priority as normal. There will then be another cleanup step after the first cleanup step. The turn won't end until there's a cleanup step in which nothing triggers and players don't get priority.In the scenario you describe, Archfiend of Ifnir will trigger for each card you discard. Those triggers will go on the stack and resolve one by one. Generous Patron will trigger for each creature that gets a counter from Archfiend's trigger, causing you to draw that many cards. When the new cleanup step starts, you'll have to discard to hand size again, which will trigger Archfiend again, which will trigger Patron again, etc. This process will continue until either your opponent has no creatures left that can get -1/-1 counters or you lose from drawing your whole deck.
