Required Libraries and Addons:
LibAddonMenu-2.0
Echoing Vigor in ESO is a skill which does not have smart targeting. As a result, the combination of factors required to determine the correct moment to cast Echoing Vigor is far from trivial.
Firstly this addon will track your casts of Echoing Vigor, and ignore anyone else's (for example if you have 2 healers in a trial using this skill).
These appear to be the rules that ESO uses when you cast Echoing Vigor in a group of 12 people.
1. All targets outside of 15 meters from the caster are ignored
2. The maximum number of people that can receive the HOT per cast is 6
3. Preferentially players with lower health by percentage will receive the heal, however in many situations most if not all of the team will have full or near full HP.
4. Echoing vigor will next try to apply to players that already have Echoing Vigor active.
Item 4: is the main problem with Echoing Vigor. As it will prefer to re-apply to the same targets you already have the HOT on, thus making double casting mostly ineffective.
Ideally it would apply to players who do not have Echoing Vigor, thus making 2 casts of Echoing Vigor in a trial cover everyone.
This addon will make an attempt to determine if casting Echoing Vigor will actually apply to new players, or if it will mostly be refreshing the HOT on people that already have it.
You can adjust the setting "Targets in Trials" to determine the number of guaranteed new targets before the Echoing Vigor cast is recommended by changing the background of the addon to RED.
Color based Echoing Vigor Status
Customizable Interface