"Just my fcking luck!" Arnold yelled while the horde of undead kept chasing him, "Fck! All the traps will get triggered if I don't put a stop to their rampage soon."
Arnold severely underestimated the intelligence of the Elven Lich. He thought he would simply kill the lich with a bullet and be done with that. Easy peasy. Sadly, he did exactly what the Undead Elf wanted him to.
Arnold's bullet blew the lich's head off as he had desired, but the bullet wasn't able to finish the lich off. Because the lich's 'soul' wasn't in his body, but somewhere else... or in other words, inside one of his undead minions. At least that was what System-sama told him. Even if Arnold was to used his deadliest of abilities on the lich, the lich simply regenerated back to all its glory.