Originally posted by Hobo Misanthropus:

It's definitely possible, but not only is it going to suck massive amounts of ass to go into the mistlands without the wisplight, as ineffectual as it ends up being, it's still better than blind, fighting through an infested mines with Iron Tier weapons is wildly inadvisable.

I think the wisplight is absolutely not necessary for Mistlands. I've already tried to play without killing Yagluth getting most of the Mistland crafting items including magic staves.
Feather cloak was definitely one of the first obvious choices as it makes travelling in Mistlands so much more comfortable.