Some Bonus Cards seem to require knowing what enemies you’ll be facing on a given Floor, such as Spider Speed Limit or Flameproof Undies. There are some clues you can pick up while you’re playing to make an educated guess at what you’ll face on the next Floor so you can use the best card.
The first and usually the most obvious clue is the name of the Floor. They often have clever names such as The Boneyard, Den of Spiders, or Face the Fire that will give you a pretty good idea of what you’ll be facing.
The second clue might be a little less obvious. While you’re running through a Floor you can see part of the next Floor at the very top of your screen. A glimpse or two up to the top of your screen while you’re running through a floor can give you a very good idea of the layout and types of enemies coming your way next. Obviously spending too much time looking at the next Floor can be risky, so do be careful.