Uses for Oblique Case

The oblique works as saying "any other type of case". Depending on the meaning, some specific cases aren't marked with a posposition.

With instruments and tools: Oblique works as an instrumental case. Comitative is marked with posposition, same to dative, locative...

With people and animals: Oblique works as dative. Rest of cases have to be marked

With gerunds and participles: It works as a dative

Rest of syntactic complements need prepositions.