Octaves 12 and 13 are quite different from the corresponding verses in Gerusalemme Liberata, but no 'compared criticism' will be done here since the GC version is much more interesting. But, later on, it will be very interesting to see octave 15 both as it appeared in GL and as it has been modified in GC.
Here above, the quite unusual description of God as a vampire comes from Dante, Paradiso 27: 58-59, in a heartfelt invective by St Peter himself who however referred to the 14th century Papacy, namely Clement V and John XXII who "are about to drink our very blood."
The image of the devils' "then bright faces being turned into appalling faces" will be powerfully reworked by Milton in Paradise Lost 1: 84 ff:
"If thou beest he - but O how fall'n! how changed
From him, who in the happy realms of light
Clothed with transcendent brightness didst outshine
Myriads though bright . . ."