Death animation followed by explosion

A simple way to do this would be to use a coroutine:

 public override void Die() {
     StartCoroutine("DieAnim");
 }
     
 IEnumerator DieAnim() {
             animator.SetTrigger("Destroyed");
             yield return new WaitForSeconds(3.0f); // The length of your animation...
             player.AddExperience(expOnDeath);
             base.Die();
             AudioSource.PlayClipAtPoint(blastSound, transform.position);
             Instantiate (explosion,transform.position,transform.rotation);
             yield return null;
         }

unfortunately I wasn't able to get this to work. I got the error

 VerificationException: Error verifying Spidey/<DieAnim>c__Iterator2:MoveNext (): Cannot call a non-final virtual method from an objet diferent thant the this pointer at 0x0077
 UnityEngine.MonoBehaviour:StartCoroutine(String)

I did get it to work however, though maybe not the best method, but I used these two scripts. Basically I created a script for the spider enemy instead of using a super and then set up an empty gameObject (that followed the player with incrementTowards) to instantiate an explosion and then be destroyed when the spider enemy was null.

 using UnityEngine;
 using System.Collections;

 public class SpiderEnemy : MonoBehaviour
 {
 
 public float expOnDeath; 
 private PlayerLevel player;
 public float Health;
 public Animator animator;

 
 void Start()
 {
     player = GameObject.FindGameObjectWithTag("PlayerLevel").GetComponent<PlayerLevel>(); // find our gameObject tagged player and access the - Player script -
 }

 public void TakeDamage(float dmg) // virtual is being used so we can override a method in the subclass
 {
     Health -= dmg;
     
     if(Health <= 0)
     {
         Collapse();
     }
     
 }
 
 public  void Collapse() 
 {                                                
     animator.SetTrigger("Destroyed");
     player.AddExperience(expOnDeath);
     Destroy(gameObject, 3);
 }

}

&&

 using UnityEngine;
 using System.Collections;

 public class ExplodingSpider : MonoBehaviour 
 {
 public Transform target;
 private Quaternion rotation;
 public GameObject explosion;
 public AudioClip blastSound;
 public SpiderEnemy spider;
 private bool explode;
 private float trackSpeed = 10;
 

 void LateUpdate () 
 {
     if (target) //if there is a target (so if our gameObject wasn't destroyed) 
     {
         float x = IncrementTowards(target.position.x, target.position.x, trackSpeed); // having the x and y position of our camera match the target position and change its transform.position accordingly
         float y = IncrementTowards(target.position.y, target.position.y, trackSpeed);
         float z = IncrementTowards(target.position.z, target.position.z, trackSpeed);
         transform.position = new Vector3 (x,y,z);                                     // camera is following the player // changing its position according to the position of the player
     }


     if(spider == null)
     {
         BigBang();
     }
 }

 private float IncrementTowards(float n, float target, float a) // arguments  //float n is "current speed" // target which is the first var in the update function // acceleration..how fast it is incrementing// currentSpeed = Increment Towards ( currentSpeed, targetSpeed, acceleration);
 {
     if (n == target) // if the current speed is already equal to the target speed then just return the current speed. // (0==0) return 0  (8==8) return 8 best guess
     {
         return n;   // if n is already equal to the target then we can just return the current speed i.e. when the function is called just return n as our value
     }
     else 
     {
         float dir = Mathf.Sign(target - n); // must n be increased or decreased to get closer to target // Return value is 1 when f is positive or zero, -1 when f is negative.
         n += a * Time.deltaTime * dir;  // incrementing current speed by the acceleration multiplied by the direction 
         return (dir == Mathf.Sign(target - n))? n: target; // if n has now passed target, then return target otherwise return n
     }
 }

 public void ResetTarget()
 {
     target = GameObject.FindGameObjectWithTag("Player").transform;
 }

 private void BigBang()
 {
     AudioSource.PlayClipAtPoint(blastSound, transform.position);
     Instantiate (explosion,transform.position,transform.rotation);
     Destroy (gameObject);
 }