The total amount of damage in ESO is calculated by the damage of each ability you deal against a single enemy or multiple enemies. Single target is often referred to as ST damage and multiple targets are often referred to as AoE damage.
The damage of an ability can be increase by increasing your spell/weapon damage and magicka/stamina. 1 spell damage is worth around 10.5 magicka. 1 weapon damage is worth around 10.5 stamina. For example, that means every 1000 magicka is worth approximately 95 spell damage.
