When used, your pet will miraculously return to life with full health.
Heart of the Phoenix is a core ferocitypet ability that allows the hunter's pet to return to life after dying.
A note on usage: the ability does not work automatically. You must click on the button once your pet is dead to make it work. You can put the button to cast this in pet's mini-bar. You can also write a macro to create a button to cast it.