полиморф

Character.php

<?php
  abstract class Character
 {
    public $lvl= 1;
    public $name;
    public $power;
    public $intellect;

    abstract function updateStat();

    public function __construct($name)
    {
        $this->name = $name;
    }

      function levelUp($level)
      {
          $this->lvl = $level;
          return $this->updateStat();
      }
    public function  getStat()
    {
        echo  '<h1>' . $this->name . '</h1>'.'интелект' . $this->intellect . '<br>' . 'сила' . $this->power;
    }
 }

Mage.php

<?php
require_once "Character.php";
class Mage extends Character
{
    public $intellect = 2;
    public $power = 1;

    function updateStat()
    {
        $this->power = $this->lvl -1 + ($this->power + 1);
        $this->intellect =  $this->lvl * 2 + ($this->intellect );

    }
}
$mage = new Mage('Mage');
$mage->getStat();
$mage->levelUp(10);
$mage->getStat();
$mage->levelUp(1);
$mage->getStat();

Warrior.php

<?php
require_once "Character.php";
class Warrior extends Character
{
    public $intellect = 1;
    public $power = 2;

    function updateStat()
    {
            $this->intellect = $this->lvl -1 + ($this->intellect + 1);
            $this->power =  $this->lvl * 2 + ($this->power );

    }

}
$warrior = new Warrior('Warrior');
$warrior->getStat();
$warrior->levelUp(10);
$warrior->getStat();
$warrior->levelUp(1);
$warrior->getStat();