Summary
Actually to make certain skills do stuff depending on the amount of stacks an aura has been applied on an entity I use metadata/scoreboard, but it ends up being a mess because of all the cleaning that is needed after the skill is no longer being used (deleting scoreboard variables, reseting the meta values...) All of this would be better if there was a placeholder that returned the amount of stacks applied of a certain aura.
Usage
It would be used as any other placeholder, for example, if someone wants to make a skill that heals depending on the amount of stacks of an aura called "light":
- heal{a='5 * <caster.aurastacks.light>} @self
Value
It would be a small step to more intuitive skill making. As I said, it's already possible to do skills like these with scoreboard and such, but it becomes a mess and also takes some time to figure it out completly.
Priority
Low. There won't be a lot of skills using this placeholder, so it can be delayed if necessary
Implementation
Describe how you think your suggestion should be implemented.