Using Oath Points
Each oath point can be used to improve the degree of success of a single skill test by one step - but only if the test is relevant to the oath in question. For example, a fumbled roll could be upgraded to a mere failure, whereas a failed roll could be upgraded to a success, or a successful test could be upgraded to a critical success.
Alternately, a character also has the option of spending three oath points to improve the degree of success of a single skill test by two steps (i.e. to increase a failure to a critical success for example).
However, any success that is raised to a critical with the use of oath points is simply regarded as a critical for the purpose of determining the outcome of the test, and any additional benefits of a 'natural' critical (such as maximum damage from combat attacks, a lower magic point cost when casting spells, etc.) do not apply. Also note that, in the case of opposed tests, a character that uses an oath point is considered to have rolled the absolute best he/she could have done for the new result - i.e. a character that raises a failed roll to a success is assumed to have rolled exactly the same as his/her skill value (see page 16 of the main rulebook for more information on opposed skill tests).
Once oath points are used they are gone forever - though players can of course trade in more improvement/fate points to gain additional oath points (or indeed to swear a new oath*) when they become available.
So, if we stick with the previous example (where a character with 3 oath points has sworn to slay beastlings wherever he/she finds them), that character may utilise his/her oath points to increase the degree of success of three separate skill tests by one step (or one skill test by two steps) - so long as those skills pertain to the combating and tracking of beastlings.
As you can see, oath points not only grant characters a substantial boost to certain actions when they need them most, but they may also inspire moments of great role-playing as players strive to act in accordance with the oaths that their characters have sworn. On the other hand, the regular loss of improvement/fate points can be somewhat detrimental to the advancement of the character in the long run, if that character becomes obsessed with fulfilling his/her oath.
*See multiple oaths
next up ...Fulfilling an Oath