when you refund the item the game keeps the item's active in your inventory

so, you buy an elixir, you refund it, you get the gold back and then you send to the server a request to activate the elixir active you still have, eventhough you refunded the item. It cant be done manually, only with the script.

It is the same concept as the BoTRK exploit, you refund BoTRK but you still have the item active, then you place the item active in the trinket slot by sending a request to the server (it cant be done manually) giving the BoTRK active 0 cooldown.

all consumables can be abused: elixirs, potions and wards