So, based on .hint() and $hint official documentation, I'm using this query on terminal:

db.Logs.find()._addSpecial( "$hint", { $natural : -1 } )

The closest I was able to produce on C# was something like:

var options = new FindOptions
            {
                Modifiers = new MongoDB.Bson.BsonDocument("$hint", "{ $natural : -1 }")
            };

//let me check the "translation"
var str = logCollection.Find(obj => true, options).ToString();

return logCollection.Find(obj => true, options).ToList();

This code throws the exception:

planner returned error :: caused by :: hint provided does not correspond to an existing index.'

But, the '.ToString()' method does seems to translate the command correctly:

find({ })._addSpecial("$hint", "{ $natural : -1 }")

So, if ToString() is getting it correctly, it should work, but it isn't.

On that note, shouldn't you create an C# equivalent to find().hint(index) to make it simpler to use hint ?