Fortune begets fortune. Misfortune begets fortune. That is the
blessing of Tymora.

Encounter ✦     Divine
No Action      Personal

Channel Divinity: You can use only one channel divinity power per encounter

Trigger: You roll a natural 1 or natural 20 on an attack roll or saving throw

Effect: Once before the end of your next turn, you can roll d20 twice for an attack roll or a saving throw and use whichever d20 result you prefer.

Published in Forgotten Realms Player's Guide, page(s) 137.