Second Chance

Second Chance
Feat
Prerequisite: Race: halfling

Fortune favors you when someone tries to strike you. You gain the following benefits:
- When a creature you can see hits you with an attack roll, you can use your reaction to force that creature to reroll. Once you use this ability, you can't use it again until you roll initiative at the start of combat or until you finish a short or long rest.

Source: Xanathar's Guide to Everything (XGE), page 75