How Armor Works

Armor Class (AC)

AC shows how easy (or hard) it is to land a hit when you attack with a weapon, fist, arrow, etc. Everyone starts at 10. Only shields, Dexterity ability bonus, magic items, or magic can raise or lower it.

Armor does not change AC. Even a knight in full plate can still be struck – AC is about whether the attack connects, while armor itself provides Damage Reduction (DR). A shield gives a +2 to AC.

Damage Reduction (DR)

Armor protects by reducing damage once a hit lands. Each type of armor has a flat DR value that is subtracted from the physical damage taken.

Creatures, monsters, etc. may have a physical or magical component that raises their DR naturally.

Shields do not have DR and do not reduce damage. A shield raises AC, making it harder to hit you. A natural 20 ignores DR completely.

Critical Hits

A critical hit occurs when you roll a natural 20 on a 1d20. This causes two times more damage. Critical hits bypass DR – no matter the protection, a perfect strike ignores all DR.