Evidence taken and filtering of that info is just one of the responsibilities of a Special Master. Trump has a whole list of issues, besides what was taken, with the warrant that they can look into. Getting people under oath with regard to how the warrant was processed and how executive privilege was denied will put a lot of pressure on the fbi and doj.

See below taken from one of the many online descriptions of a Special Master:

The Special Master has the authority to regulate all proceedings and to compel the production of documents and other evidence. In addition, the master may put witnesses and parties under oath and may examine them. Once the evidence has been taken, the special master files a report with the appointing court. This report may contain findings of fact and conclusions of law. Once a master's report has been filed in a non-jury case, the court must accept the findings of fact unless they are clearly erroneous