When that happens they give you a repeatable Exsanguinate which is a sorcery for a reason
While the obvious first home for Urza's Cave is Tron decks as a failsafe for games where it's difficult to assemble the three Urza lands necessary for the strategy's explosive mana acceleration , it's also interesting to consider what else Urza's Cave can do in decks featuring Knight of the Reliquary, Elvish Reclaimer, and the Modern Horizons 3 reprint Sylvan Safekeeper
The second activates when you use the first, creating a 1/1 Spirit creature with flying whenever you exile one or more cards from your hand or battlefield
As far as R&D is concerned, it is the theme discard cards that cause the most unhappiness as discard decks are one of the scary three (land destruction, permission and discard) that tend to keep people from playing the game and thus tend to annoy players at a much higher level than other decks
Brawl Legal Vintage Legal Timeless Legal Commander Legal Pauper Not Legal Oathbreaker Legal Penny Legal Toolbox Buy This Card Notes and Rules Information for Avatar Aang // Aang, Master of Elements: An ability that triggers "whenever you waterbend" triggers whenever you pay a waterbend cost, regardless of how you paid that cost
