Frenzy is a Berserker Barbarian feature gained at level 3 in D&D 5e. Starting when you choose this path at 3rd level, you can go into a frenzy when you rage.
Starting when you choose this path at 3rd level, you can go into a frenzy when you rage. If you do so, for the duration of your rage you can make a single melee weapon attack as a bonus action on each of your turns after this one. When your rage ends, you suffer one level of exhaustion (as described in appendix A).