It would be great to be able to use wildcard collections when creating privileges for user roles, for example:

db.createRole(
   {
     role: "manageCustomCollections",
     privileges: [
       { resource: { db: "data", collection: "custom.*" }, actions: [ "find", "update", "insert", "remove" ] }
     ],
     ...
   }
)

This would make it easier for administrators to manage permissions for a set of collections by removing the need to explicitly specify each collection.