allow me to do bulk changes
I'd like to change many cards at once. Let me filter a list and/or select multiple cards and do some common things like change the owner, set the priority, move to done, add a comment, etc.

In the 4.15 release we have provided bulk operation support on the Kanban board.Please check the below help link for details.
http://help.swiftkanban.com/getting-started/projects/cards/bulk-operations-on-card.html
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David Starr commented
THis works great in Kanbanize. Loo at their UX implementation of being able to select multiple cards.
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Daniel Oh commented
Bulk linking would also be very useful. Even though it seems that most users create Epics > USTs > Tasks in that order, establishing hierarchy as they go, there are many use cases for creating lower level tasks first and then associating these to existing USTs and Epics. Thanks.