Item combine??

Item combine??

Hi: I need some help, I want combine items in my map like DotA(when a hero buy a Recipe inmediatly remove some items for make an other item)for example when you buy "Ring of health" an "Void Stone" inmediatly these items make a "Perseverance", How can i do that???

suppose that a+b+recipe = c

then make a trigger:

Event:
Uni - Acquire an Item

Conditions:
Item Type of item being manipulated equal to recipe
Hero has Item type of a
Hero has item type of b

Actions:
Drop item type of recipe from triggering unit
Remove last dropped item
Drop item type of a from triggering unit
Remove last dropped item
Drop item type of b from triggering unit
Remove last dropped item
Create 1 item type c for triggering unit
Create special effect (whataver you want on triggering unit)

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