There are two special instances of natural rolls, which apply during attack rolls:
- Natural 20 - For an attack roll, results in an automatic hit, and likely a Critical Hit (also known as "Crit").
- Natural 1 - For an attack roll, results in an automatic miss.
- Very often, DMs may inject house rules to apply natural 1 or Natural 20s to have other effects. In some cases, these may be benign such as having them automatically pass or fail a skill check or saving throw, but can often appear as dangerous combat where a natural 1 causes an automatic crit on all your party members.