Buying abilities from a store

i want to make it so i can buy abilities from a store|||I am doing the same for a shop on my map, i'll post the triggers here when i'm done.

The way i plan to do it is use items bought from the shop to learn to abilities. For example, i get my "priest" to buy a "tome of heal". I make a trigger that activates upon use of the "tome of heal" that checks if it is the "priest" using it, if so, teaches the priest the spell "heal". The "tome of heal" itself will do nothing without the trigger.

The quotations are just outlining examples, they could be anything.|||Yea, what LazyTom said, but without the intermediate step.

Make an item with the same name and icon as the ability you want. Make sure you have "Use Automatically when Acquired" set to true. Make a trigger with the event being "Unit Uses an Item", the condition "Item = whatever item you want to cause the ability upgrade", and the action "give unit ability X".

So what the player sees is that he buys an ability at a store and he gets his ability.

What is really happening is the player buys a dummy item that looks like the ability, he'll use it automatically, and then a triggering gives him that ability.