Glen the gnome ranger takes aim at the Tarasque and fires his short bow. Clark the player running Glen rolls a 20. The Tarasque is hit. Clark then rolls his percentile dice and it comes up 97 with a slight gasp at the table Clark now rolls the damage 3d6 + modifiers.
Wait 3d6 but a short bow only does a single d6 what gives, is this Glen a rouge as well? The short answer is no.
The longer answer:
We use the percentile die when we roll critical hits at the table. This is a simple table as well . Anything less than 90 you roll the damage die two times. 90-98 you roll the damage die three times. 99-100 is an instant kill. This can add some fun to your table if you let it like in the experience of Clark and his Gnome Ranger Glen.