Yhyjyk

A couple days ago, a friend sent me an excerpt from a new game, asking about a Latin phrase in it:

Contra Diabolus enim et alii Daemones

(In the game, this is the motto of a group of Catholic monster hunters—so it's meant to be Church Latin, not Classical.)

The translation seems fairly straightforward: "Against the Devil and other Demons". I would have used diabolum in the accusative, but that's a separate matter.

What confused me, though, was the word enim in the middle. I would normally translate enim as "for" or "because". So what's it doing here, right before et? Is it just an error on the translator's part, or is this a usage of enim I'm not familiar with?

A quick web search shows that the phrase 'Diabolus enim et alii Daemones' (without the contra) appears to originate from the Fourth Council of the Lateran (1215). The full sentence is Diabolus enim et alii daemones a Deo quidem natura creati sunt boni, sed ipsi per se facti sunt mali, which I would translate as something like, 'For the Devil and other demons were created by God (to be) good by nature, it's true, but they became, on their own, through their own agency, wicked.'

I suspect that whoever created the phrase for the game knew of this sentence, knew that contra means 'against', but didn't know that it requires a change of case or that enim doesn't really belong unless it's serving a connecting function; therefore, he or she just stuck contra at the beginning instead of changing to contra Diabolum et alios daemones.

I would indeed expect the accusatives Diabolum and alios together with contra.
But there is a way to make the nominative work; then contra has to be read as an adverb, not a preposition (which would require accusative).
Ignoring the enim, the whole phrase could be read as "in front [of us are] the Devil and other Demons".

To make sense of enim, I think it modifies the entire motto, not just the second part.
It usually comes as the second word, but if the first two words are closely connected, it can come a little later.
This tight connection would make sense for me if contra was used as a preposition, but not so much in the adverbial use.
I find the position a little odd but not completely wrong.

As Leqis and Short write, enim is a corroborative particle.
An apt English counterpart here might be "indeed".
Therefore I would read the whole as:

In front [of us are] indeed the Devil and other Demons

However, this does feel a little odd.
Enim is in a weird place (and not even necessary in my opinion), and the use of contra strikes me as weird too.
The motto may well be a well-composed Latin motto, but it could also be a mistaken attempt at translating "Against the Devil and other Demons".