Item collection

[Foxace]

How to build system where unit is unlocked if player collects certain amount of items? Also what item stacks? I want item to stack for an example 10 times and then it can be converted into item which can be used to summon special unit.

 

[deathismyfriend]

Having an item change into something else would be an item recipe system. There is one in my sig.
If it is just a certain item count then add up items when unit picks up the item. When it reaches your number do actions.

 

[Foxace]

But how to make unit stack?

Items should be inactive until there are 10 items and then player click the 10 item stack and unit is summoned if unit is in summoning area.

 

[Meticulous]

Add charges to the item via triggers whenever a new one is picked up, and remove the newly acquired item. Ideally you have two items - one that is used instantly when acquired, and one that you add to the unit's inventory through a trigger when the used instantly item is used. Otherwise your unit won't be able to pick up another charge if its inventory is full.