How do skills like "echoing vigor" choose their targets?
Well, many skills work differently. E.g. you cannot apply the working of echoing vigor with radiating regeneration. They are different.

In case of echoing vigor:
1) If i press it once, 6 players get the heal over time. Who gets the heal over time and why?
- If none of the players have missing health, always the same six players (if in range) will get the hot. I'm not sure how they get picked, might be based on how the group was built (e.g. first six players - but i'm not really sure how they exactly are determined).
- If players have missing health, these players will get the hot.
- if more than 6 players have missing health: idk, maybe the same 6 again or based missing on health. I have not tested this yet.
2) If i press it again what happens?
- the same six players will get the hot unless someone has not full health.
3) How many players can 1 person heal with this skill at the same time?
- you can only give 1 stack of this hot to a player. If a player has already that hot from you on him, it will be refreshed.
- If you cast it multiple times and if you are lucky (players taking damage and different players get hit by the hot), everyone in the group can have a stack of the hot up and running.

This means if you have 12 players in the group in theory the result may look quite differently depending on the situation. If everyone casts echoing vigor:
- All at full health -> 6players with 12 stacks, 6 players with 0 stacks
- If all players had lost some health and echoing vigor was casted multiple times by each player -> 12 players with 12 stacks

In reality it might be somewhere in between.

At least that was how it worked a patch or two ago. Might have missed that they have changed something here...

YandereGirlfriend wrote: »

The poster above does a fantastic job explaining this important, but completely neglected in terms of presentation to the player, aspect of the game.

To add something to the conversation, I believe that the Smart Healing targets are selected by lowest Max HP when all players in range are at full Health.

To add a little bit more: OP, welcome to the wide world of target caps in ESO. Many/most buff and debuff skills have an unadvertised target cap of 6, this includes player abilities and things like sets and CP stars. If you want to provide a buff or heal to your entire group, much thought and care is required as you frequently have to meta-game these invisible target caps.

Target caps are certainly an annoyance. This is why you see many trial groups split into 2 stacks, to ensure buffs can be applied to everyone without the same 6 getting them and others neglected. IMO the target cap should be the same as the group cap, 12 players.

Of course certain skills can still target fewer, such as Twilight Matriarch (2) and Radiating Regeneration (3). These are fine for smart targeting low health allies, but buffs and area effects should work on all allies in that area.