ive looked online but none worked

You make a collision by hitting two physics objects against eachother. You reference that collision in C# scripts with one of the following, depending on your needs: OnCollisionEnter() OnCollisionExit() OnCollisionStay()

void OnCollisionEnter(Collision collision) {

   if(collision.transform.CompareTag("Spike"){

     health--;

     Destroy(collision.transform.gameObject);

}

}