Piercer

Piercer
Feat
Prerequisite: Level 4

You gain the following benefits.
Puncture.
Once per turn, when you hit a creature with an attack that deals Piercing damage, you can reroll one of the attack's damage dice, and you must use the new roll.
Enhanced Critical.
When you score a Critical Hit that deals Piercing damage to a creature, you can roll one additional damage die when determining the extra Piercing damage the target takes.

Source: Player's Handbook (2024) (XPHB), page 206