Using non owned skins in New Draft, Client/Gameplay

Was in the new draft mode, And I switched with my jungler who wanted kha'zix while I wanted to go kassadin. Well, I selected my cosmic Reaver Kass skin and the client switched it to Festival kassadin which I do not own that skin. So when I saw it in the loading screen. I thought It might be a graphic bug but turns out that I got to use festival kassadin for free.