You can assign any item for a quick purchase. To do this you need to hold down Shift and the Left mouse button and then click on any item.
As soon as you accumulate enough money to purchase an item (or one of its parts), you hear a beep, and the object which is now available to buy will be framed.
You can assign hotkey for "quick purchase" in the game settings. For example, I use a combination of Alt + A.
What happens if you added in the fast purchase an item that consists of several items? For example, if you have just 200 coins, and you have Soul ring 
in the "Quick Buy", by pressing hotkey you will buy a recipe. But if you have 500 coins you
will automatically purchase the most left item on the list.
If you placed Hex 
into the "Quick Buy" and have enough money to buy any part of
it, using the hotkey will lead to buying the 
if you're not close to the Secret
Shop.
To remove an item from "Quick Buy" you should click the red X in the same window, or hold down Shift and click the left mouse button. Or just click on another item in the shop to replace the current one.
"Sticky" item is in the same window as "Quick Buy" items. To set a hotkey for the purchase of this item, you should appoint desired key / combination of keys in the setting's stock "Purchase Sticky".
To change "Sticky" item, you simply drag and drop the icon of your desired artifact into the 
's place.
Informing Allies
To inform the allies about which item you intend to buy, you need to hold down ALT and click on the item. But if you are holding ALT and clicking on the object you have in "Quick Buy" you will tell team how much gold you need to collect to make the purchase.
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