Does one of the enemy cards delete a card from your deck or something? I've been trying making decks and when I go for a minimum deck size style I tend to notice that I've gone from 12/10 to 11/9 at some point and with enemy cards not doing the same things as player cards it's kind of hard to figure out what's happening since I also can't check their deck or trash.
Also static doesn't have an explanation on the tutorial and the last time I tried to hover over something with it applied I didn't see any tooltip