I remember back on Parler someone was telling me how they replaced their D20s with 20 card decks for a session as an experiment. The result was their players being a lot more wary as their deck whittled down as this made 1s & 20s were guaranteed. What are some interesting mechanics or tricks that you have used to change player behavior? I've been playing with the idea of using blackjack with limited hits for rolls. How would you react? would you risk a critical failure(21+) to get a critical success(21) or would you play it safe & only use the hits you need to inch over the DC?