With the release today of Plasma 5.11 beta it is time again to use kde-next for the next 3 weeks or so.
https://www.kde.org/announcements/plasma-5.10.95.php
Packages are up:
http://kaosx.tk/packages/index.php?subdir=kde-next&sortby=name
New additions include plasma-vault and the split of drkonqi away from plasma-workspace into a standalone package.
Also new is powerdevil build with ddcutil, this gives extra option to adjust monitor settings (like brightness and color levels).
As always add kde-next as the first option in your pacman.conf and make sure the build repo is also enable.
If you do not know how to adjust for that, then please don't try to use kde-next, adjusting pacman.conf is by far the easiest part of helping with testing. Just wait a few weeks until is stable and well tested, then it will land in the regular apps repo.