Durability is one of the primary stats of a character from a VS Debating standpoint. It refers to the amount of energy it takes to damage a character. Not to be confused with Stamina, which only refers to the amount of time it takes a character to fight before tiring out.
Given Newton's Third Law of Motion, every action has an equal and opposite reaction, meaning that when an object exerts any amount of force, it is met with a force of equal potency. In most cases, characters are not physically damaged when performing a notable feat, so it is logical for their durability to be equal to their attack potency. However, this might not always be the case, as sometimes feats are caused by sources other than one's physical power. For example, a feat performed by a character who needs a specific weapon to perform this feat would not scale to the wielder's physicality, but the durability of the weapon itself. It is suggested to be careful when dealing with similar cases.
As for rankings, durability uses the exact same level system as Attack Potency. If you wish to consult that, please refer to the Attack Potency article.