Bil ur-sag (de Morbid angel)
(www.acordesytabs.com)
RIFF 1

1  | -------------------- |  (You have to stop the chords)
2  | -------------------- | 
3  | -------------------- | 
4  | 5-----6-----6-5----- | 
5  | 3--6--4--5--4-3-5-6- | 
6  | ---4-----3------3-4- | 

RIFF 2

1 | --------------------- |  (I am not really sure of the 4 slided notes
2 | --------------------- | 
3 | --------------------- | 
4 | --------------------- | 
5 | 333---444------------ | 
6 | ---444---333-98/4- | 

RIFF 3

1 | ---------------------------- | -------------------------------- | 
2 | ---------------------------- | -------------------------------- | 
3 | ---------------------------- | -------------------------------- | 
4 | -------------/5-4-3--------- | -------------/5-4-3-5----------- | 
5 | ---------------------------- | -------------------------------- | 
6 | 0-0-0-0-0-0-0------3-2h3-2h3 | 0-0-0-0-0-0-0--------2h3-2h3---- | 

RIFF 4

1 | --------------------------------------------------------------- | 
2 | --------------------------------------------------------------- |          
3 | --------------------------------------------------------------- | 
4 | -7h10-7h10-7h10-8h11-8h11-8h11-7h10-7h10-7h10-10h13-10h13-10h13 | 
5 | --------------------------------------------------------------- | 
6 | --------------------------------------------------------------- | 

RIFF 5

1 | --------------------------- | 
2 | --------------------------- | 
3 | --------------------------- | 
4 | --------------------------- | 
5 | 7x7x7-8x8x8-7x7x7-10x10x10- | 
6 | 5x5x5-6x6x6-5x5x5-8-x8-x8-- | 

RIFF 6

1 | ----------------------------------- |  
2 | ----------------------------------- | 
3 | ----------------------------------- | 
4 | ----------------------------------- | 
5 | ----------------------------------- | 
6 | 0-0-0-0-0-0-0-0/3-3-3-3-3-3-3-2h3p2 |  Play it thrice and the fourth time play:

1 | -------------------------------- | 
2 | -------------------------------- | 
3 | -------------------------------- | 
4 | -------------------------------- | 
5 | -------------------------------- | 
6 | 0-0-0-0-0-0-0-0-2-2-2-2-2-2-2-2- | 
                  p.m.____________]

Legend:
,/ : slide            x    : percusion mute
h   : hammer on            p.m. : palm muting
p   : pull off            ___] : length of p.m.

Structure:

Intro   :Riff 1 x2; Riff2 x4
Verse 1 :Riff 2 x4
Chorus  :Riff 3 x1; Riff4 x1/2
Intro   :same
Verse 2 :same 
Chorus  ;Riff 3 x1;Riff4 X4 (with some variations)
Solo 1  ;Riff 5 x4 (I could not find the solos but if you do, please tell me!)
Bridge  ;Riff 6 X1 
Solo 2  ;Riff 6 x1
Intro   ;Riff 2 x2(drum only*) x2(gtrs); Riff 1 x2
Verse 3 ; same
Chorus  ;Riff 3 x1
Final   ;Riff 4 (once more with variations)

*: to play the "Riff2" on drum , your drummer needs at least 4 toms.