From Dawn of Corruption Wiki
Tiadane's name has spread beyond the confines of time and space.
How to Unlock
Skip the minotaur fight by telling him the right name.
In front of Apothus' hideout, right before fighting the Minotaur, he'll ask you who you're looking for. If you say "Tiadane" (his real name), you'll skip the fight and obtain the Achievement.
Strength + 10
XP Multiplier + 0.3
In-game, the only way to learn the Minotaur's name is to obtain the ending [Memories of the Minotaur]. But it isn't mandatory to have the related achievement to obtain this one.
You can also tell to the Minotaur "Cray", "Apothus", "Nyx", "Sombreve" or "Kanathar". These will not allow you to skip the fight, but will each trigger different reactions.