Path of the beating heart

An ancient barbarian was on the brink of death, when a sympathetic sorcerer used magic to revitalize the barbarians heart. However, this both blessed and cursed the barbarians heart, giving it some interesting effects

Hearts blessing

Because of the blessing on your heart, you heal 3d4 health when you exit your rage

Accelerated heart

When you start raging, your heart starts to beat faster. This gives you one fourth of your max hp rounded down as temporary hit points.  This also gives you disadvantage on CON rolls

Hearts curse

Because of the curse on your heart, you will receive an extra 1d4 of damage when hit