Remember the time you accidentally bought a Doran's Blade instead of a Doran's Ring? It may not have been the reason you lost, but it probably didn't help. Those days are coming to an end for League of Legends ' players because Riot has added an undo button to the shop on the PBE server. Now, when you misclick and buy a Wriggle's Lantern instead of a Vamp Scepter, you can get a full refund.
It works by maintaining a history of the items that you've purchased or sold. As long as you stay on the platform, you can undo your most recent transaction. Certain purchases like the Homeguard enchantment will clear your item history and cannot be undone. Elixirs that are consumed when you buy them can't be refunded either. Oh, and casting a spell, using an item, and dealing or taking damage, all clear your history. Riot really has thought of everything—even the gold you accrue from a Philosopher's Stone will be deducted from your refund.
The undo button may not be live on the standard servers yet, but expect the ability to undo your in-game sales and purchases soon. Check out this thread for more information.