In The Picture of Dorian Gray Oscar Wilde uses epigrams, aphorisms, rich descriptions, and irony to describe the transformation of Dorian Gray into this new Hedonistic person that Lord Henry has lured him to turn into.
One specific ironic moment is Dorian's reaction to the death of Sybil Vane. When Basil goes to Dorian's house to comfort and ease him over the death of Sybil, Dorian simply said that Sybil should be proud to have lived her passion to the last, and that she died like a heroine in a Shakespeare play, which is what she did for a living.
To this, of course, Basil reacted in shock, since Dorian made this statement merely a day after Sybil was found dead and called the incident to be "a thing of the past".
Additionally, Wilde presents how the transformation of Dorian is correlated to the deterioration of his picture. It is in chapters 9-12 where you find him at his most hedonistic, and more extreme while the picture is shockingly hideous. Therefore, the irony of the whole thing is more palpable in this part of the story and is perhaps one of the place where more rhetorical strategies can be witnessed in the story.