Every living creature has an established Hit Dice, which indicates the relative power of the creature, its hit points, ability to hit opponents in combat and its saving throw. Hit dice are assigned arbitrarily to creatures, to create a list of monsters that offer a varying threat to the player characters.
Hit dice should not be confused with experience levels, which are a measurement of how much experience and training a character possesses. Additional hit points are gained from levels and added to the character's natural hit dice.
For each hit die that a creature possesses, it is allotted a random number of hit points per die. This number is determined by the creature's mass. Very large creatures with few hit dice may have a great many hit points; whereas a very tiny creature with many hit dice, but a very small mass, may have few hit points.
Attacking in Combat