Zombie Horde, eh? Well theres quite a number of 'last stand' or 'ultimate battle' themes I could use. Starting with Ultimate Battle from Plants vs Zombies, for laughs.
or Vanquish the Horrible Night (Castlevania 2 tribute by Powerglove)
or for best results, Leeroy Jenkins fun times mix, why go in only half-assed?
Yep I realized he's fighting dragons, I mean it more for the 'lets do this' aspect.