"Don't ask the gods!"
Translation:Nolite deos rogare!
Dei can be used as the nominative plural (although if I remember correctly di is commonly used since deus is irregular) and the genitive singular. Deus is the nominative singular form.
The reason dei is not accepted for a valid translation is because the gods are the ones being asked, they are the direct object of rogare and must be in the accusative plural deos.
dei rogant -> "the gods ask"
deos rogant -> "they ask the gods"
I fully understand that (same with other languages, but yes, particularly when it comes to latin). But sometimes it helps to 'break' things down and look at the Grammar rules applied in the language one speaks, to better grasp the grammar in the language to-be-learnt. So coming back to my way of grasping: I do think that 'touch' in the English sentence here is indeed infinitive. From this understanding I can easily understand the 'rogare' - the latin infinitive.