When you want to represent the passage of time or events leading to a dramatic climax—such as an impending adversary move or a significant narrative event—you can use your d20 or another die as a countdown die to track that progression. Choose a die with your desired starting value on it and put it on the table with that number facing up. For example, if your starting value is 5, you can use a d6 set to 5 as your countdown die.

Each time the countdown ticks down, turn the die to reduce its value by one. When the countdown ticks down from 1 to 0 (which doesn’t appear on the die), the countdown ends and triggers the event you were counting down to. If you ever need to continue a countdown across sessions, record the current countdown value so you can continue counting next session.

If you don’t want to use dice to track your countdowns, you can alternatively draw a number of small boxes equal to the starting value and fill them in as the countdown progresses.