Fun game, it's got the goal of blackjack (get 21 or get cloase to it) but because the playstyle is different (both you and your opponent are playing at the same time) You could just stand on 16 or 15 instead depending if the opponent stood on 17 or 18. (It's better to take the 1, 2 or 3 points of damage instead of recieving 17 or 18 points of damage) because you will recover your health in the future.
Also just a personal critique, but destroying a card permanently after the 2nd or 3rd encounter is way to early in my opinion. Since you haven't developed your deck to be bigger than intended, or found a card that doesn't help your type of deck build. (Maybe when moving to the next level (like Tarvern to Basement) It'd cost you to give up a card in your deck as payment perhaps?)
Excited for the full release, wishing you all the best in development!