Tales of the Bloodstone Lands
A Circumstance Bonus is a DM bonus (or penalty) imposed for favorable or unfavorable circumstance. It usually results in a +1 or -1 to the check. Circumstance bonuses do not stack, either things are favorable or unfavorable. However Circumstance Bonuses and Penalties do cancel each other out.do
This may cover many situations, and includes the use of special equipment. If a piece of equipment provides a circumstance bonus, it will say so in its write-up.
Examples: A Listening Horn provides a circumstance bonus when making Perception checks to listen at a door. The Tome known as the Maleficarum provides a circumstance bonus when researching information about devils and the Hells.