Well, I have just competed the game with Mr Fisto, my guy with an Int of 1. So he's a combat machine (not that he could spell either of those big words) and he utterly hammers into Mr Cheif Bad Guy (no spoilers) with Kryggid's Falchion (a very nice peice of cutlery, that.). Interesting is that I don't need to use the vedigroth device! I just keep whacking him and he drops dead, and the game ends! Strange, that. I thought it was utterly necessarry! Maybe once I return to Arcanum I could sell it somewhere... Thinking of which, is there any way to return to Arcanum from the void? I seem to find lots of gems etc, as well as Torian Kel's sword. How do I do this, or is it just teasing me?
I've never heard of killing him without the vedigroth device, so you've got me stumped there. However, you can't return to Arcanum while you're in the void. You should take everything you need, cause you aren't getting back out.
You can use Kryggid's Falchion to kill Kerghan or Arronax instead of the Vendigroth Device. It's to help those poor people who misplace their Vendigroth Device or forget to bring it to the Void with them. That way, they still get to finish the game.
