The only Wizard in town
Dresden is ironically suspected of having killed two people, as their cause of death was magical. This is ironic because he is actually innocent and has only been accused due to the fact he is a wizard, so there is actually no evidence to support this accusation.
Dresden
Harry Dresden is ironically a kind wizard who uses his powers to help people. However, he is then accused of killing people by Murphy.
ThreeEye
The drug ThreeEye is initially used to make humans temporarily magical. However, after using this drug for some time they ironically become insane.
Urban fantasy
This book takes typical fantastic elements such as wizards and makes them part of the normal world. This is ironic because often these realms aren't mixed in fiction.
Dresden as a detective
Ironically, Harry must solve the murder he is accused of doing. This is because otherwise he might be convicted of this murder without fair evidence.