Critical Hits in Combat

If the d20 roll for an attack is a 20, the attack hits regardless of any modifiers or the target’s AC. This is called a critical hit.¹

Rules as written: When you score a critical hit, you get to roll extra dice for the attack’s damage against the target. Roll all of the attack’s damage dice twice and add them together. Then add any relevant modifiers as normal. To speed up play, you can roll all the damage dice at once.

For example, if you score a critical hit with a dagger, roll 2d4 for the damage, rather than 1d4, and then add your relevant ability modifier. If the attack involves other damage dice, such as from the rogue’s Sneak Attack feature, you roll those dice twice as well.²

Critical Hits in Chronala (House Rule): When you score a critical hit, instead of rolling extra dice for the attack’s damage against the target, you automatically get the maximum damage you would normally do, plus rolling your normal damage. As with the Rules as Written, any modifiers only apply once. Roll all of the attack’s damage dice twice and add them together. Then add any relevant modifiers as normal. To speed up play, you can roll all the damage dice at once.

For example, if you score a critical hit with a dagger, you do 4 points of damage for the critical plus roll 1d4 and then add your relevant ability modifier for what would have been normal damage. If the attack involves other damage dice, such as from the rogue’s Sneak Attack feature, you would roll your normal damage then add what would be the maximum amount of that damage type for the critical.

¹ Player's Handbook, Chapter 9: Combat > Making an Attack > Attack Rolls > Rolling a 1 or 20

² Player's Handbook, Chapter 9: Combat > Damage & Healing > Damage Rolls > Critical Hits