Notification of work task step completed

I went to send an email  to an user when the work task step state changes to work done.  This email needs to list all the lines on the task step.

What is the best way to achieve this please ?

1. Custom event 
   1. Execute Online sql code using the command_sys.mail command
   2. Create a crystal report and then using custom event email action type add the crystal report with the details

Any help greatfully received