Criticals and Fumbles (Combat)

Criticals and Fumbles occurr when the dice comes up with an extreme result, 1 or 20.

Fumbles

A roll of 1 is considered a Fumble. This means that, almost always, the attack has failed.

If a roll of 1 would have succeeded (due to modifiers), make a new attack roll with -20 To-Hit. If this attack would hit the target, it is not a Fumble but deals minimum damage. If the character would be incapable of this on a re-roll, they do not make a new roll - it is a miss. A re-roll from a Fumble cannot be a Critical or a Critical Hit.

Critical

A roll of 20 is considered a Critical. This means, almost always, the attack is a hit and may be a Critical Hit.

To determine if a Critical hits, compare the effective AC hit to the target's AC and roll damage. If you could lower the effective AC hit by 10 or less and still hit, the attack automatically hits. For every 5 points you would need to decrease the To-Hit Roll's value by, after the first 10, half the effective damage done. The first time this is done will deal 1/2 damage, then 1/4 damage, then 1/8 damage and so on. If reduced to between 1 and half a point of damage, 1 point of damage is still dealt. If this would reduce it below half a point of damage, then no damage is dealt and the attack probably misses.

For example, a character has an effective THAC0 of 18 and rolls 20 on the dice. 18 - 20 gives them a To-Hit roll of -2. Their target is a shadow dragon with AC -12. This is exactly 10 lower than their attack and so it hits normally! If, however, it was darker and the effective THAC0 were 20, this means they would hit AC 0. With the target's AC being 12 points below this, the attack will only do half damage.

This range of values where the character may get a successful hit on a Critical is to prevent situations where a character may somehow achieve a hit from the other side of the planet on a 1 in 20 chance.

Note, Critical Range effects only when Critical Hits can occur, not the automatic hit qualities of a Critical roll.

Critical Hit

When a Critical is rolled, or if an attack roll falls within the Critical Range of an attack, it may be a Critical Hit.

If the attack qualifies for the above and would successfully hit by 5 or more, the attack is a Critical Hit and the character may roll for Severity. In the interest of speed of play, a player may opt to instead roll damage twice or do maximum normal weapon damage without rolling for Severity.

For example, a character has an effective THAC0 of 16 and rolls 20. This gives them a To-Hit Roll of -4. As their target has an AC of 2, they successfully hit by 6. This constitutes a Critical Hit.

The Hit-By-5 rule is to prevent situations where a target with a high AC may only be missed 95% of the time or hit and a Critical Hit is scored automatically.