Hmm, I wonder, when he told that guy to die, he did, but since his slaves were connected to him, the "die" command spread through the connect, weakening the power of it. Thus, his slaves died, but command wasn't powerful enough,s o they turned into undead. As for the attacking everything, he was talking about destroying the city to kill the MC, so maybe that thought got stuck in the the zombies heads through his slave connection.