Critical Roll

A critical roll occurs when a ten-sided die lands on '10' (often labeled as '0' on the die.) You must then flip a coin. If you call it correctly, that die is a critical success, otherwise it is a critical failure.

Critical Success

You performed flawlessly. In some rare instances, you may still fall short of your intended goal, but you will likely bring about an additional, positive side effect.

Critical Failure

You performed dismally. In some rare instances, you may still achieve your intended goal, but you will likely bring about some additional, adverse effect.

Advantage and Disadvantage and Critical Rolls

When you have Advantages or Disadvantages, treat every die as separate in terms of critical rolls. For example, if you have two Advantages and happen to roll three '10's, you would then flip a coin for each die (3 in total.) Since only the highest result is kept, you will likely be able to discard any critical failures, barring the unfortunate instance where you fail all three coun tosses.

Variants

Instead of flipping a coin, you could instead roll the die again, treating an odd number as a critical failure and an even number as a critical success.

Instead of flipping a coin, you could achieve the same results by using d10ish dice in place of the normal d10 dice. Each d10ish die is a 20-sided die that has 1 through 9 twice and 0 and 10 only once. Rolling a 0 on a d10ish die is a critical failure while rolling a 10 is a critical success.

The same effect of a d10ish die can be achieved using a 20-sided die by subtracting 10 from any result of 10 and higher, with a 0 (10 on the d20) being a critical failure and a 10 (20 on the d20) being a critical success.