Drop D.
Intro
e|--------------------------------------------------------
B|----------------X4------------------------X4------------
G|Clean--------------------------Heavy--------------------
D|-Part-----4----4---4-0---4-0---Part--5-5-5-5-4-4-4-4-4-4  
A|--------5----5---2-----2-------------5-5-5-5-4-4-4-2-2-2
D|------5----5-------------------------5-5-5-5-4-4-4------

Verse after bass alone
e|------------------------------------
B|------------------------------------
G|-4----------------------------------
D|-4--5--0-0-0-0----X4----------------
A|-2--5--0-0-0-0----------------------
D|----5--0-0-0-0----------------------

Chorus
e|---------------------------------------
B|---------------------------------------
G|--2-2-2-2-7-7-7-7--4-4-4-4-------------
D|--2-2-2-2-7-7-7-7--4-4-4-4-5--5-5-5----
A|--0-0-0-0-5-5-5-5--2-2-2-2-5--5-5-5----
D|---------------------------5--5-5-5----

These are the main riffs threwout the song.