This section covers the rules for attacks, including how to make them, how armor class works, as well as their bonuses and penalties.
You make an attack when you attempt to hit a target with a spell, a weapon, or while unarmed against the target's armor class (or "AC"). Roll a d20 and apply any bonuses and penalties you might have to the attack. If the total equals or exceeds the target's AC, the attack is a hit, and you roll the attack's damage. Otherwise, the attack is a miss.
Your armor class (or "AC") determines how well you avoid being hit by an attack. While you have no armor equipped (or unarmored), your AC is 10 + your Dexterity modifier, whereas certain armor, artifacts, and spells, as well as character, item, or environmental features grant different ways to determine your AC, or grant different bonuses and penalties to it.
An attack roll can have one or more bonuses and penalties, and can be made with different uses.
When you make an attack roll, you add your attribute score modifier to the attack and damage rolls: for melee weapons or while unarmed, add your Strength modifier; for ranged weapons, add your Dexterity modifier; and for spells, add your spellcasting attribute modifier.
Certain conditions apply bonuses or penalties to an attack roll, such as the charmed, covered, degraded, empowered, exposed, marked, prone, staggered, strained, submerged, threatened, unconscious, and unstable.
There are two types of critical scores: a critical hit and a critical miss. Each of these critical scores have their own threshold.
Attack rolls have a critical hit threshold: any roll of 20 on the d20 is a critical hit, causing the attack to hit the target regardless of its Amor Class, and the attack's damage die is rolled twice. If the attack roll total is equal to or higher than twice the target's AC, the damage's die becomes explosive. An armor subjected to a critical hit becomes degraded.
Attacks have a critical miss threshold: any roll of 1 on the d20 is a critical miss, causing the attack to miss the target. A weapon subjected to a critical miss becomes degraded, and a spell becomes fizzled until the spellcaster finishes a rest.
When you make an attack roll with a weapon you have training with, you can add the associated training bonus to the roll.