How do you kill a summoned phoenix?

The Phoenix isn't exactly a level 7 creature. If it's a neutral unit, there won't be any problems, especially with a decent hero. However, if the Phoenix is summoned by a powerful mage, that's a real problem. It has around 1000 HP, if I'm not mistaken, and it moves quickly, so it's unlikely you'll be able to do anything before it attacks. If I were playing as Haven, I would buff my troops, reduce its stats as much as possible, and simply overwhelm it with my entire army. It's easier to deal with as Necropolis or Inferno.