Combat Reflexes (5e Feat)
From D&D Wiki
Prerequisites: Dexterity 13 or higher
Your reflexes have been honed to such a degree that you may take addition reactions each round of combat.
- You gain a number of additional reactions each round equal to your Dexterity bonus.
- You may make attacks of opportunity while surprised.
- A character without this feat can make only one reaction per round.
- A character without this feat can't make attacks of opportunity while surprised.