So, just searched for this exploit existing, and this thread exists:
http://www.mmowned.com/forums/wow-ex...full-heal.html
Which basically says, you can switch a piece of gear, and when you do, you immediately regain full health. But, if you're in combat as a zombie, you can't switch your armor, and your weapons are gone because as a zombie, you're "disarmed".
EASY SOLUTION: MAKE A MACRO TO SWITCH YOUR WAND/BOW/GUN OUT!
On my warlock, as a zombie, made a fast macro to
/equip Vengeful Gladiator's Piercing touch
/equip Brutal Gladiator's Piercing touch
And then I just SPAMMED it, and, unless you're stunned, you're invincible! NOW RUN AROUND AND INFECT THE WHOLE WORLD!!!