User blog comment:Pualover/Overlord Power Level/@comment-26815449-20150911042309/@comment-26836039-20150911103138

I re-read that part and I can infer the following: When someone kill a dragon, he is called a "Dragon Slayer". There's no specific passage that says a Dragon Slayer is a Hero rank but it is high likely the case. Killing a dragon is usually done by a group of adventurers or more. Of course a Dragon Zombie is an exception whose level is probably 30-35 because Gagaran alone can kill one. A live dragon's level should be 40 or greater. This could be an understatement since all dragon lords are around 80. That's a really huge gap. Thanks I'll add the Dragon Zombie and Dragon to the list.