Trickster's Ace Feat 18
Source Pathfinder Advanced Player's Guide
Trigger You specify the trigger when you make your daily preparations (see Requirements below).
Requirements When you make your daily preparations, you must specify a trigger for this reaction using the same restrictions as the triggers for the Ready action. You also choose a single spell from the arcane, divine, occult, or primal list of 4th level or lower. The spell can't have a cost, nor can its casting time be more than 10 minutes. The spell must be able to target a single creature, and you must be a valid target for it.
Whether from jury-rigged magic items, deduction from the study of magical interactions, or other means, you have a contingency in your back pocket for desperate situations.
When the trigger occurs, you cause the spell to come into effect. The spell targets only you, no matter how many creatures it would affect normally. If you define particularly complicated conditions, as determined by the GM, the trigger might fail. Once the contingency is triggered, the spell is expended until your next daily preparations.
Traits
Anything that doesn't list another rarity trait (uncommon, rare, or unique) automatically has the common trait. This rarity indicates that an ability, item, or spell is available to all players who meet the prerequisites for it. A creature of this rarity is generally known and can be summoned with the appropriate summon spell.
ConcentrateAn action with this trait requires a degree of mental concentration and discipline.
InvestigatorThis indicates abilities from the investigator class.
RogueThis indicates abilities from the rogue class.