I have found technology to work extremely well for formative assessment.

A summative assessment will affect the student mark so one should be extremely careful
before trying to be creative or to use technology. If you are going to be creative try
to do so long before the final exam.

Your formative and summative assessment approaches should complement each other. I recommend treating the formative assessment as
an assignment not worth more than 10%.

A proper assessment strategy can improve the efficiencly of your teaching. Do not improvise as you go. Students have a right to know how they will be evaluated very early in the process.

P.S. Keep in mind that Midterms and finals serve different purposes. Midterms are in part motivational and also serve as a buffer in case the finals are not representative.

It is relatively hard to improve one's delivery skills but quite easy to improve one's assessment skills by reading the proper articles.
Assessment is more of a science than an art.

Gilbert