diff --git a/constructors.js b/constructors.js
index d0bf11a..e48f07a 100644
--- a/constructors.js
+++ b/constructors.js
@@ -10,7 +10,11 @@
  * @property {string} description
  * @method   printDetails
  */
-
+function Spell (name, cost, description) {
+   this.name = name;
+   this.cost = cost;
+   this.description = description;
+}
   /**
    * Returns a string of all of the spell's details.
    * The format doesn't matter, as long as it contains the spell name, cost, and description.
@@ -18,6 +22,9 @@
    * @name getDetails
    * @return {string} details containing all of the spells information.
    */
+   Spell.prototype.getDetails = function () {
+      return 'You called ' + this.name + ' which costs ' + this.cost + ' and ' + this.description;
+   };
 
 /**
  * A spell that deals damage.
@@ -43,7 +50,16 @@
  * @property {number} damage
  * @property {string} description
  */
+function DamageSpell (name, cost, damage, description) {
+   this.damage = damage;
+   Spell.call(this, name, cost, description);
+}
 
+DamageSpell.prototype = Object.create(Spell.prototype, {
+   constructor: {
+      value: DamageSpell
+   }
+});
 /**
  * Now that you've created some spells, let's create
  * `Spellcaster` objects that can use them!
@@ -60,6 +76,12 @@
  * @method  spendMana
  * @method  invoke
  */
+function Spellcaster (name, health, mana) {
+   this.name = name;
+   this.health = health;
+   this.mana = mana;
+   this.isAlive = true;
+}
 
   /**
    * @method inflictDamage
@@ -71,6 +93,14 @@
    *
    * @param  {number} damage  Amount of damage to deal to the spellcaster
    */
+Spellcaster.prototype.inflictDamage = function (damage) {
+   this.health -= damage;
+
+   if (this.health <= 0) {
+      this.health = 0;
+      this.isAlive = false;
+   }
+};
 
   /**
    * @method spendMana
@@ -81,7 +111,13 @@
    * @param  {number} cost      The amount of mana to spend.
    * @return {boolean} success  Whether mana was successfully spent.
    */
-
+Spellcaster.prototype.spendMana = function (cost) {
+   if (this.mana >= cost) {
+      this.mana -= cost;
+      return true;
+   }
+   return false;
+};
   /**
    * @method invoke
    *
@@ -108,3 +144,22 @@
    * @param  {Spellcaster} target         The spell target to be inflicted.
    * @return {boolean}                    Whether the spell was successfully cast.
    */
+Spellcaster.prototype.invoke = function (spell, target) {
+   if (!(spell instanceof Spell)) {
+      return false;
+   }
+   if (spell instanceof DamageSpell) {
+
+      if (target instanceof Spellcaster) {
+
+         if (this.spendMana(spell.cost)) {
+
+            target.inflictDamage(spell.damage);
+            return true;
+         }
+         return false;
+      }
+      return false;
+   }
+   return this.spendMana(spell.cost);
+};
\ No newline at end of file