Many Fate spells bestow a boon on the subject, that can provide a number of positive effects.
Boons can impose one of the following effects:
Grant 9-Again quality on a number of mundane dice rolls equal to Potency for the Duration of the spell.
The subject’s player can choose which of his rolls are affected by this Boon (declared before the dice are rolled).
If used on a chance roll, the subject does not gain the 9-Again quality, but the chance die is treated as a single die instead of as a chance die.
By adding +1 Reach this becomes 8-Again, instead.
The Boon may also affect spellcasting rolls and other powers at the cost of +2 Reach.
Grant a dice bonus equal to Potency on certain actions (usually a single Skill) for a number of rolls equal to the Potency of the spell during its Duration.
Multiple boons cannot grant their bonus to the same action; only the highest bonus counts.
The subject’s player chooses which of his rolls are affected by this Boon before rolling the dice.
Grant a number of beneficial Conditions (such as Charmed, Informed, Inspired, or Steadfast) equal to Potency for the Duration of the spell.
None of these Conditions grant Beats when the subject resolves them (unless the caster achieved an exceptional success in the casting).
As with Hexes, Potency can be used to mix and match the above effects, Boons that affect the same Skill do not combine their effects (only the highest bonus counts), and no character can have multiple instances of a Condition unless they apply to two different and specific things.