Editing Open4E: Core Mechanic (section)

==Check Modifiers==
Each time you make a check, one or more modifiers will most likely apply to the roll. Modifiers go in two directions - bonuses are added to your die roll, while penalties are subtracted from it.

===Bonuses===
Most bonuses come from a particular source; these modifiers will have an adjective to describe them, such as feat bonuses or class bonuses or circumstance bonuses or racial bonuses. If several bonuses apply to the roll you are about to make that all have the same adjective, only the highest one applies, and only once. For example, if you have a +2 class bonus to saving throws, and a +5 class bonus to saving throws vs. charm effects, then you apply the +5 modifier when making a saving throw vs. a charm effect, not the +7 that you would get from adding them together. However, if you have two different bonuses, such as a +2 class bonus and a +3 proficiency bonus, you may add them both to the roll. Untyped bonuses are bonuses which have no type - you add all of these together when you make your roll.

===Penalties===
Penalties, on the other hand, always accumulate regardless of their source. While many penalties will have adjectives, the adjectives are only important when specific powers or capabilities allow you to reduce or ignore a particular type of penalty; once you are ready to roll the dice, add all penalties that apply to the dice roll together and subtract that from the result.