ESO addon BuffTheGroup - BTG
https://www.esoui.com/downloads/fileinfo.php?id=2759#info
A small simple UI that allows you to track a single buff across all your group members. Useful as support classes and dps tracking Powerful Assault, Major Slayer, and other buffs that your group members want.
The UI appears when you enter a group zone (Trial, Dungeon, Arena).