Using the Lightning Conductor Add-In for SharePoint Online, we build a few different rollup scenarios, to rollup SharePoint Task Lists within SharePoint Online. We use the built in JSON Timeline view to display Tasks rolled up from multiple site collections and display them in a timeline view similar to that found in out-of-the-box SharePoint Task Lists. We also display the Tasks within a calendar. The Calendar XSLT view is built into the Lightning Conductor which allows for either calendar lists or task lists to be displayed in calendar format. Finally, we modify the existing Tasks view to group by Task Status, and build a calculated column.