Finesse is a resource mechanic that builds through successful performance in Elder Scrolls Online combat. Bonus Finesse is awarded for “playing smart”, for example, interrupting an enemy spell cast or blocking a dangerous attack will boost your Finesse. Groups of players can rapidly accumulate Finesse by performing attack combos that use Synergy Abilities to produce a special effect. Completing an encounter with high Finesse yields additional rewards, ranging from a small experience boost to additional magical loot.
Synergy Abilities are what happens when multiple players executing skills together to create a powerful magical effect by combining multiple abilities. These cross-class combo opportunities will prompt visual cues on the screen to help parties effectively combine their powers. For example, a sorcerer can cast firestorm and the eso dragonknight can run into the middle of that and cast Bladestorm, which would cause a spray of fireballs in a 360-degree radius. Enemy creatures will work together if they cross paths, and the enemy UI is smart enough to exploit the same Synergies against the player. Enemies can and will team up to use their superior numbers against the player. These Synergy Abilities work both ways, and a successful group will have to both employ their own cross-class combos, as well prevent their enemies from doing the same.
Enemies also have a Factional Synergy. Opponents belonging to the same political group can combine their abilities for combat bonuses unique to that political group. Combat, class, and Ultimate abilities may be changed whenever you want, provided that you are not in combat. Because The Elder Scrolls Online uses a smaller number of active combat abilities than most other games, the design team is ensuring that every ability a player can use is awesome and powerful, while eliminating those filler abilities that provide only supplementary benefit.
There’s not very much information released about healing abilities. As far as I know, the healing abilities are available as class abilities for many classes, as well as weapon abilities when using stuff like the restoration staff. Most heals are either a radial or conal area-of-effect. That means that, basically, most healing abilities are AOE, either in front of the player or around the player, although there are some single-target abilities also.