Bonuses
You can gain various different bonuses to increase the results of a 1d20 roll and sometimes other rolls. These bonuses include Advantage, Assist, Deflection, Disadvantage, Dodge, Insight, Item, and Morale bonus.
Advantage and Disadvantage. With these bonuses you always roll an extra 1d20. If you have advantage, you take the better result of the two rolls. If you have disadvantage, you take the worse result of the two rolls. These always stack, so if you have advantage from two different sources you roll 1d20 three times and take the best result. When you have two different advantages it is called double advantage. The same concept in reverse applies to disadvantage, so double disadvantage is rolling three times and taking the worst result. Advantage and disadvantage cancel each other out. For example, if you have advantage on a roll from an ability but disadvantage on that same roll from a condition you roll only once.
Deflection and Dodge. These bonuses always apply to you Armor Class. All Deflection bonuses stack. Dodge bonuses do not, rather you simply take the highest bonus.
Assist, Insight, Luck, and Morale. These are often extra dice you roll and add the results to a 1d20 roll. All Insight bonuses stack. You can have up to three Assist bonuses on a check. You can have a maximum of one Luck bonus and one Morale bonus apply to a check.
Item. Item bonuses can apply to a 1d20 roll or Armor Class. It should be noted you can have only up to two Item bonuses on a check or applying to AC. Armor and Shield bonuses are not considered Item bonuses for the purpose of this limit.
Flat DCs
A Flat DC is when you roll a 1d20 with no bonuses and attempt to get equal to or higher than the DC. A Flat DC is often between a 5 and 15 but can be raised or lowered depending on the likelihood of success. For example, most Persistent Damage have a Flat DC 20 to represent how difficult it is to stop continued damage from inflicted wounds.
Criticals
The Forge System has critical successes and critical failures. A critical success is either a natural 20 on the 1d20 or 10 or more over the DC of the check. A critical failure is either a natural 1 on a 1d20 or 10 or less under the DC of the check. Criticals are most commonly applied to attack rolls and sometimes may be applied to skill checks, ability checks, and saves at the GM’s discretion.
Damage. When an attack roll is a critical, roll double the original damage dice. All weapons and abilities with the supernatural tag have their dice doubled. But not every other source of damage has the dice doubled. The following sources of damage do get doubled:
- Dead Shot
- Formless Mastery
- Powerful Stance
The following sources of damage do not get doubled:
- Elemental Fury
- Elemental Stance
- Hammerblow
- Precise Strike
- Weapon Training
- Witch Hunter
As for equipment, most sources of extra damage do not get doubled.
Saves. A critical failure on a saving throw often means the results are worse. For example, a critical failure on an initial save against a poison means starting at Stage 2. This is not universally true. For example, critically failing a Reflex to avoid falling does not double the falling damage. Follow common sense when applying critical failure to saves.
Skills. Critical successes and failures can also impact skill checks, though the results are more situational and given to the GM to determine the exact results. It is recommended that critical successes on skill provide in more accurate, more detailed, or more information or better results while critical failures mean false information or far worse situations.
Immunities, Resistances, and Weaknesses
Immunities, Resistances, and Weaknesses of creatures indicate how effects and damage interact with that creature. Immunities are effects and damage types which a creature is unaffected by, while resistances are effects and damage against which a creature is not fully affected by. Weaknesses are effects and damage against which a creature is more susceptible. The following lists the particular details of each.
Resistances lessen the amount of damage you take of a particular type. Resistance will always list a tag and value. Every time you take damage with that tag, subtract the resistance value from the tagged damage you are dealt before you apply it to your hit points. Some resistances are against all damage.
Immunities have a type. Immunities will always list a tag and you ignore all damage that has that tag.
Weaknesses also have a type. Weaknesses will always list a tag and you take double damage by multiplying the original damage by two, that has that tag.
Flanking
Flanking, which is defined as having an ally adjacent and attacking to the same enemy as you are, imparts no benefits except if you or your ally possesses abilities that utilize flanking. Very few abilities impart benefits towards flanking.