listen for timing.
E|--------------------|

intro riff / right before main riff
E|-------------------------|
B|----12----15----13----15-|
G|-12----12----12----12----|
D|-------------------------|
A|-------------------------|
E|-------------------------|

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

"wind-down" riff 1
E|----15~----------------|
B|--------15~-12h13~-12~-|
G|-12--------------------|
D|-----------------------|
A|-----------------------|
E|-----------------------|

"wind-down" riff 2 / pre-intro riff
E|--------------------------------------|
B|-------------12h13-/15~-13~-12h13p12~-|
G|-------12h14--------------------------|
D|-12h14--------------------------------|
A|--------------------------------------|
E|--------------------------------------|

and sometimes before they go into
the main riff, they play this:
E|--------------------|
B|-12h13~-12~---------|
G|------------14~-12~-|
D|--------------------|
A|--------------------|
E|--------------------|