item enhancing spell

[Kartron]

how do i make an item that enhances a hero x spell when he gets the item, something like aghanis scepter from dota

 

[Nichilus]

the spell's damage calculation is probably completely triggered to check if unit has item(s) which increases that spell's damage.

 

[Kartron]

and how would it work on a passive skill? (regen aura)

 

[Nichilus]

You would still need to trigger it, albeit maybe differently; or trigger the whole spell yourself.

If you have a passive skill and there are items which increase the effectiveness of this skill (but they don't stack if you have them all in inventory), then you can make another level of the passive skill and change the level via trigger.

For example you have Hp regen aura which regenerates 6 health per second.
Now you have an item which increases effectiveness of this Hp regen aura by 50% (thus to 9 health per second) - I'll call it "IMBA Scepter".
So what you could do is make the Hp regen aura have 2 levels - first heals 6 hp per sec, 2nd lvl heals 9 hp per sec.

Then you make a trigger which fires when "unit acquires an item", you check if the item is IMBA Scepter. If yes, you increase levle of Hp regen aura.
Then you make another trigger which fires when "unit loses an item", check if it's IMBA Scepter. Then also loop through each item slot of triggering unit (to check if this unit does not have more than 1 IMBA Scepters in inventory). If it has only 1 (= that's the one it will lose in a moment), you decrease level of Hp regen aura.

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Of course this is speaking that you have 1 (or more) item which increases the effectiveness of a spell by same amount.
If you have a list of items that increase effectiveness - for example like this:

Item1 = 23% bonus
Item2 = 7% bonus
Item3 = 10% bonus
Item4 = 17% bonus
Item5 = 9% bonus
Item6 = 5% bonus
Item7 = 25% bonus

then it will be very inefficient doing it via ability level like I proposed above, in fact it will be a lot better to trigger the whole spell yourself.