mass re-assignment of tasks

@garym - Yes, you can automate this.
Create the Portal Task Report -> Write an Expression rule with the function a!queryProcessAnalytics() and pass the above Report and the target User as Context Parameters along with the Batch Size & Sorting parameters for the Result-Set Manipulation -> Now create a process model -> Set the Start Index, Batch Size & Loop Counter -> Call the Expression Rule by passing the necessary parameters -> Fetch the Task Ids out of the Result-Set -> Convert the list to Number(Integer) type, if needed -> Call the Smart Service by passing the necessary parameters with MNI (Multiple Node Instances), if needed -> Set the Start Index, Batch Size & Loop Counter as per the need and you are done.
Though it is a one time job process, it contains both Looping and MNI so be conscious.

@poorna - thank you so much :)