Allusive speech, writing, or art is full of indirect references to people or things. (Collins Dictionary)
Containing or full of allusions. (Collins Dictionary)
Difficult to describe, find, achieve, or remember. (Cambridge Dictionary)
Using or containing suggestion rather than explicit mention. (Oxford Dictionaries)
Containing a lot of allusions. (Cambridge Dictionary)
How to use allusive, elusive or illusive.
An allusive writing: Machiavelli’s Castruccio Castracani