Zhentarim Tactics

Zhentarim Tactics
Feat
Prerequisite: Level 4

You gain the following benefits.
Retaliate.
Immediately after a creature within 5 feet of you hits you with a melee attack, you can make an Opportunity Attack against that creature.
Versatile Merc.
When you finish a Long Rest, choose a skill in which you have proficiency. You have Expertise in that skill until you finish your next Long Rest.

Source: Forgotten Realms: Heroes of Faerûn (FRHoF), page 41