From the Talisman Core Rulebook, p. 20: " The last space on the board is the Crown of Command. It can only be reached from the Valley of Fire space, which can only be entered by characters that have a Talisman. " 

So by that reasoning, you *can't* actually teleport to the Crown of Command after defeating the Lord of Darkness even though it says it teleports you to the Crown of Command when you beat it by 8 points?

When the base game was released, there were no dungeon
or other methods to get to the crown, as such, that paragraph
is correct for the base game.

Expansions build on previous mechanics and/or rules and
modify them sometimes.

So the answer is: "Yes, you can move from the Treasure Chamber
to the Crown of Command after defeating the Lord of Darkness
with a high enough score.

Thank you.