well srry i dont know how to use the trigger tag, so..
to do this, you need to make dying hero has a "corpse" :
1.)when your hero's health reaches 2%(for example) make him invulnerable and play his death animation. pause him too.(do this via triggers)
2.)make a spell based on war stomp(but I recommend Fan Of Knives), trigger that if that spell is cast nearby the hero "corpse" he will be restored to full health and mana, reset his animation, unpause him and make him vulnerable. He is "revived".
problem solved!