Ghost - Infestissumam (2013)
"Infestissumam" is the superlative form of "infestus - hostile, threatening, dangerous". It's accusative case feminine: whom? - "the most hostile one". Because of the "u" instead of "i" it sounds like archaic Latin - like the English pronouns "thou" and "thee".
The lyrics are written in Latin and Italian, although the grammar isn't always correct:
Il padre - The father
Il filio - The son
Et lo spiritus malum - and the bad spirit
Omnis caelestis - every celestial one
Delenda est - must be destroyed
Anti Cristus - Antichrist
Il filio de Sathanas - Satan's son
Anti Cristus - Antichrist
Il filio de Sathanas - Satan's son
Infestissumam - the most hostile one (again, this is feminine!)
The second song is called: Per aspera ad inferi. This means "Through hardships into the hell." The grammatically correct phrase would be: per aspera ad inferos.