Editing Mano a Mano:Success Rolls (section)

===Circumstance Modifiers===

Environment and hastiness can effect the difficulty of an action. Add 2 to the difficulty modifiers for unfavorable circumstances. Add 4 to the difficulty modifiers for hostile conditions. Modifiers for unfavorable circumstances and hostile conditions are not added to other modifiers for unfavorable circumstances or hostile conditions. When more than one of these modifiers apply, use the modifier which increases the difficulty the most. If multiple unfavorable circumstances compound each other, treat the combination as hostile conditions by adding 4 to the difficulty instead of 2.

Add 2 to the success modifiers for favorable circumstances, or add 4 to the success modifiers for very favorable circumstances. Modifiers for favorable or very favorable circumstances are not added to other modifiers for favorable or very favorable circumstances.  When more than one of these modifiers apply, use the best one. If a combination of favorable circumstances is much better than the individual circumstances, treat the combination as a single very favorable circumstance by adding 4 to the success modifiers instead of 2.