Fancy church Latin, not Italian. Con in this case means a "This" or "The" - note the caps. Think the declension of clavus (nail) and deus (god) are due to that. Not sure - only 3 years Latin over 20 years ago. So...
This Nail, This God... or maybe if I have that declension of God wrong... This sounds way cooler
"This nail (is) for This God"
conclavi con Dio in Italian means conclaves with God.
with nails, with god (from the band ghost) hail Satan!
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