I had to listen to the riff a hundred times over to work it out, so
a few comments wouldn't go a miss.  It's in the key of D minor.

Standard Tuning
(EADGBE)

E|---------------------------------------------------------------------------|
B|-------------15-------13---------------------------------------15-------13-|
G|----------14-----------------------15----12-14--------------14-------------|
D|-12-14-15-------15-14--------14-12-------------15--12-14-15-------15-14----|
A|---------------------------------------------------------------------------|
E|---------------------------------------------------------------------------|

E|---------------------------------------------------------------------------|
B|------------------------------------15-------13----------------15----------|
G|-------15----12-14---------------14-------------------------14----14-------|
D|-14-12-------------15---12-14-15-------15-14-------14-12-15----------15-12-|
A|---------------------------------------------------------------------------|
E|---------------------------------------------------------------------------|

E|----------------------|
B|----------15----------|
G|-------14----14-------|
D|-14-15----------15-12-|
A|----------------------|
E|----------------------|