Okay, this is what Descent sounds pretty much close to.
You can use the G string to be the guitar riffs if you use --4-0--
after each riff.

The strings go from top to bottom (E to G): 

   Intro: (let all riffs ring out a bit)
   ---0------2---------4---------5-------------0-------2------0- (let ring out)
   -------------------------------------------------------------
   -------------------------------------------------------------
   ----4-0-------4-0-------4-0------0-4-0---------4-0----4-0----

   Second part
   ---0-----2-------4-------5---------0------2--------0-4-0-4-0-4-0-4-0-0-
   -----------------------------------------------------------------------
   -----------------------------------------------------------------------
   -----4-0----4-0-----4-0----0-4-0------4-0----4-0-----------------------

    repeat intro for preverse...

    Verse: 
    ---0--00-2--2--2-0--0-00-2-0-2-0-------------------------
    ---------------------------------------------------------
    ---------------------------------------------------------
    ---------------------------------------------------------

    pre-Chorus:
    ---0-4-0-4-0-4-0-4-0-0----------------------------
    --------------------------------------------------
    --------------------------------------------------
    -------------------------------------------------- 
   
    Chorus: (repeat about six times)
    --0------2------4------5---------6----------------
    --------------------------------------------------
    --------------------------------------------------
    ----4-0-----4-0---4-0------4-0------0-00-4-0------

    Rest: 
    ---555--3-0-0-0-222--2-2-2-2--4-44-4-0-3-3-5-5--2-2-2-------
    ------------------------------------------------------------
    ------------------------------------------------------------
    ------------------------------------------------------------
 
    then repeat the da, da, da, da stuff with the intro.

    Ending: 
    ---0-----2-----4-----5-(after 3, do this:)-555--3--5-0-(let ring out)   
    -------------------------------------------------------
    -------------------------------------------------------
    ------4-0--4-0---4-0---4-5-4---------------------------

That's all, I hope you like it. I know that the song structure is a bit
misleading, but what I have down are the basic bass riffs for ya.

Thanks.