Capo on 4th fret.
Then C/G2 is going to be the same shape, but starting at the 4th fret.
Sounds like the way Lights plays it most when you hammer on with the Em and hammer on
the D-string when playing the C/G variation chord.
C/G, Em, C/G, Em, C/G2 (2x)
Where the fence is low
And the water is rising
And the fire comes down
And the dark fills the skies in