Wow I’m sorry I didn’t see this! The main way would be to conserve a die from the other events (potentially purposefully failing them depending on the difficulty and your upgrades). Kay brought up an alt rule of rolling a # of dice dependant on the tier of the characters, so 1 dice for each tier 1 but 2 dice for the tier 2 and 3 for the tier 3. Two characters can fight the boss at the same time.