It specifically says "I could bring tools from Laurion, but it'd take far too long to dig through". The point being that you can't dig through with what's currently available to you.
the artifact has other effects, i've 100%'d this version, and so far you cannot do anything in that tunnel. i see great potential for future updates though :D
as far as i know, it explodes. doesn't seem to have much else to offer, but we've gotta wait for vNext to know. i cant wait, im js dying to know what the rest of the story is.
