How to add an item ability to item?

Hello

Basically, what i want is a shop that imbues permanent items with abilities such as purge, silence and blink. So you can buy some item with no casting abilities (e.g. firehand gauntlets or arcanite shield) elsewhere and then bring it to this shop and enable it to cast any of these additional spells (So you can have blink firehands or silencing arcanite, or purging Mask of Death w00t :)).

I need two things for it to work.
First, i need a way to add an ability to item.
Second, i need a way to change the tooltip on the item to reflect the fact that it has a new ability. A trigger to append text to item tooltip would be nice.

I am using standard-issue 1.14 World Editor. Its GUI triggers do not offer any possibilities to do what i want to. I am thinking if someone could help me write some custom triggers for this ^^

I don't know JASS so I don't know what you can/can't do with it. I don't know of any way to modify an object in game. All you can do is replace it with another item with the stuff you want. I.e. the number of combos your talking about would be massive.

I stand corrected.

That only means that for every permanent item in your map, you have to make 3 new ones. Ouch...

or not.
Use an item system like DT4a (the RPG system link in my sig), and you can modify the item table directly (edit the string for abilities and add more to it), then have the hero reequip it.

The part with:

set udg_ItemArray[Ix(j,2)]="Dmg,arm,hp,mana"
set udg_ItemArray[Ix(j,3)]="Str,agi,int"
set udg_ItemArray[Ix(j,4)]="Ability to add seperate with commas"

looks very promising indeed :)

Hmmmm

So basically to add an ability to item i should use the return bug to make it a unit, add an ability to unit and then use the return bug again to remake unit into item?

No that suggestion you have wouldn't work at all I wish it would but items are just junk.
Dt4a is a handling system it basically replaces the item interface (which is junky) with a system that adds abilities directly to a unit. It also supports stuff like direct modification of Dmg, armor, hp and mana because its powered by bonus mod, and str agi int because those are natives.
My suggestion would be this:
You basically create an item like you would normally for DT4a. However after you decide you want to upgrade the item for whatever reason, you would find what item it was (very simple GetEquiped I believe returns its x value for the 2d array) then you would modify one of the fields. Then you would call reequip passing it the same item as he currently has. He should then have the item buffed.

But it wouldn't be possible to give items active abilities with this engine, would it? Abilities which activate when you click on item.

No but it could add an ability directly to your command card.

The problem is - our map is AoS map. So all heroes have at most 2 free slots in the middle row of command card. Items provide a much larger array of abilities...

Hmmm

Is there a way to identify if an item has an active ability?
If there is such a way, it is possible to create a workaround, where you create a new item with identified active ability, then add all passive abilities of the old item, then add whatever new abilities the item is supposed to have.

That still leaves us with the problem of tooltip updates, though. For clarity reasons, all tooltips on all custom-made items need to reflect their current array of abilities. Is that even possible?