Retaliation is a Berserker Barbarian feature gained at level 14 in D&D 5e. Starting at 14th level, when you take damage from a creature that is within 5 feet of you, you can use your reaction to make a melee weapon Attack against that creature.
Starting at 14th level, when you take damage from a creature that is within 5 feet of you, you can use your reaction to make a melee weapon Attack against that creature.