You touch a weapon or worn item and imbue luck into it. If imbued on a weapon, for the duration, on an attack roll, the wielder can roll an additional d20 (they can choose to do this after they roll, but before the outcome is determined). The creature can choose which of the d20s is used for the attack roll. If imbued into a worn item, they can roll a d20 when attacked, then choose whether the attack uses the attacker's roll or theirs. With either use, the spell immediately ends upon rolling the extra d20.