One of the real Hercules' 12 labors was to defeat the Lernean Hydra. This is the one labor he could not have succeeded in without the help of Iolaus. Each time Hercules cut off one of its heads two sprouted from the trunk until Iolaus cauterized it with a torch. Even then it had one more head that was immortal, so Hercules cut it off and buried it. It was still alive, but rendered helpless.