C#m          Am  Ab    E    Bm
E--4        5    4    0    7
A--4        7    6    7    9
D--6        7    6    9    9
G--6        X    X    9    X
B--5        X    X    0    X
E--4        X    X    0    X
So for the verses the tune goes

Riff 1:
C#m
Day after day as I bodies slay,And the sun becomes dark in the sky
Am
Everything's lost for this human race,And the dawn of a new age will rise
.....
Riff 2:
             Ab Am  E                     Bm
No more hope        As we raise our hands to the sky

Riff 3:
       C#m            Am         E            Bm
On the endless sea of madness we sail forever more
        C#m              Am      E                   Bm
And the endless tears of sadness towards the distant shores

Riff 4:
         Ab           Am       Bm
With the power of the almighty sword

That is the basic Verse structure
If you want to play lead
Verses:  E major pentatonic scale
Chosus:  Ebm pentatonic scale due to key change