IMO this raid had two objectives - isolate Trump legally, as fewer prominent attorneys will be willing to work with Trump after this raid, and to goad Trump to fire Mueller and spark impeachment.
Trump needs to consider his response very carefully. I would favor a two step action:
Fire Sessions
Replace him with someone who will convene a Grand Jury (or appoint a special prosecutor) and start filing charges against people. Comey for perjury, McCabe, Loretta Lynch (Obstruction) and others.
I am reminded of the Far-side Cartoon: