For 10 points, name this action which sometimes involves defeating Cerberus and encountering Persephone.
The eighth book of the Thebaid opens by describing Tisiphone being sent into battle after this action is completed by a seer who was tricked into fighting when his wife Eriphyle was bribed with the Necklace of Harmonia. That man is Amphiaraus, who does this after Zeus saves him from Poriclymenus. In one story, Psyche is told how to do this by a tower and falls into a deep sleep while doing it after Aphrodite demands that she fill a box with beauty. One way of doing this is to dig a hole at the confluence of three rivers, pour honey, milk, wine, and water into it, and cut the throats of a ram and a ewe. Odysseus violates Circe's instructions by speaking to Elpenor while completing this action and the Sibyl of Cumae tells Aeneas he'll need the Golden Bough to do it. Heracles encounters an entrapped Theseus while doing it during his 12th labor, and Orpheus does this by charming Charon. For 10 points, name this action which sometimes involves defeating Cerberus and encountering Persephone.
The eighth book of the Thebaid opens by describing Tisiphone being sent into battle after this action is completed by a seer who was tricked into fighting when his wife Eriphyle was bribed with the Necklace of Harmonia.
{visiting} the {underworld} [or {katabasis}; or {visiting Hades}; accept {logical} equivalents]