Being a retired teacher and lecturer, perhaps I may be forgiven for the sin of being too particular in matters of Classical languages.

Unfortunately the errors of Anton LaVey and those who regurgitate his words from The Satanic Bible have never been corrected.

The proper noun 'Satan' in Latin is 'Satana' - a first declension masculine noun similar to 'agricola' and is declined thus:-

Nominative    Satana
Vocative        Satana
Accusative    Satanam
Genitive         Satanae
Dative            Satanae
Ablative         Satana

Therefore, "Hail, Satan" is "Ave, Satana" (the vocative or addressing mode), not 'Satanas'.  In the 'Book of Iniquities', Matthew 4:11 it is written "Vade, Satana" ("Get thee hence, Satan" - again the vocative. )

Luke 10:18 demonstrates the accusitive case (object of the sentence): "Vidi Satanam" - "I beheld Satan."

"In the name of Satan" would take the genitive case: "In nomine Satanae."

What then is this version of the name - 'Satanas'?

'Satanas' is the Attic Greek form of the name and is declined in the following manner:-

Nominative    Satanas   Satanaj 
Vocative        Satana    Satana
Accusative    Satanan   Satanan
Genitive         Satanou   Satanou
Dative            Satana     Satanv

There is no Ablative in Greek

'Satanas' is only used when He is the subject of a sentence.

The vocative when addressing would be 'Satana' as in
"pareimi, Satana" ("pareimi, Satana") which means "Hear am I, O Satan."

I quote from Matthew 12.26:- "Kai ei o Satanaj ton Satanan ekballei"  ("Kai ei ho Satanas ton Satanan ekballei" - "And if Satan [nominative] cast out Satan" [accusitive]).

"In the Name of Satan" takes the genitive case: "onomati Satanou" ("onomati Satanou").

Corinthians 5:05 shows the use of the dative case:- "paradoumai ton toiouton tw Satanv" ("paradoumai ton toiouton to Satana" - "to hand over such a one to Satan.")   Both the omega of 'to' and the last alpha of 'Satana' have an iota subscript denoting the dative case.

These few examples should help such as call upon this deity to tidy up their grammar should they wish to use 
classical Latin or Greek.  I know that many Satanists criticise the Church of Rome, its philosophies, hypocricies, etc., but the priests of that Church at least are highly fluent in Classical languages and  can address their god using the proper grammar and syntax.

It does make one a trifle irritable when two Classical languages are mixed together (the Latin "Ave" with the Greek "Satanas") - hell knows the number of times I was given a load of grief when I could not remember a certain Latin word and substituted the Greek equivalent.  My tutor would go absolutely wild with rage!

N.B.: One requires a Greek font to read the above white Greek quotations.

Here then is an overdue gift to those who call the Dominus Infernus, or should I say "Dominum Infernum" - accusitive case, as he is the object of this phrase.