There is no limit to how many times you can duel the same person (and you can re-challenge the Club Masters too), but this is where you need to start praying to RNGesus
(To proliferate, choose any number of permanents and/or players, then give each another counter of each kind already there.) P/T Number 89 Language English Legal Formats Commander, Legacy, Vintage Not Legal Formats Alchemy, Brawl, Competitive Brawl, Historic, Modern, Pauper, Pioneer, Standard, Timeless Rulings (3/8/2024) The ability that causes Agent Frank Horrigan to have indestructible starts to apply as soon as it's declared as an attacker
But I think this is less of a power level development and more about a creativity one
#1 Stock Up Set: Aetherdrift Market Price: $7.35 When it released in Aetherdrift, Stock Up set a new baseline for the amount of card advantage and selection players should expect from a blue three-mana sorcery
Sure, you might not make a ton of money selling two Revised Volcanic Islands, maybe $50, but they are high-demand cards that are easy to move, require no sorting, and likely ship together, so all in all, you're making that $50 for very little work
