Briarheart is a medium armor set. When you deal Critical Damage, you have a 10% chance to increase your Weapon Damage by 449 for 10 seconds. While this effect is active your Critical Strikes heal you for 609 Health. This effect can occur once every 15 seconds.
Briarheart is part of the Orsinium DLC and drops in Wrothgar in the Overland content. You can also find it on Guild Traders. Each set item is bound on equip. You can acquire medium armor, jewelry and weapons for this set in the Barbaric motif style.