This is just a thought I had, really. I, at least, think it would be neat to be able to see how many NPCs I have defeated or event encounters I have had, during an event.

In example, the current October event. On the event page, spot much like the beetle tracker, that keeps track of all the rabid/nightmare enemies you've beaten. Just to see how many you've defeated over the course of the event.

This counter would change with each event. It could also have a lifetime counter under it, like the beetle counter.

Also, it could be made into an event leaderboard as well! See just how many encounters you and your fellow players have made.