[GAMEPLAY] Riven's passive works on towers

Hi, I'm really sorry but right now it's 12:30 in the morning and I'm too tired to make a recording, but I noticed that whilst in game as Riven, whenever my passive (Runic Blade) was active from casting abilities, I did bonus damage to the outer tower. I believe this also affects the inner tower, but it does NOT affect inhibitors. Furthermore, it does not actually consume the passive buff, it just simply does more damage.

To recreate this bug, simply play Riven in any Summoner's Rift game, auto attack a tower and note down the damage, following this use any ability to give yourself a stack of Runic Blade, and when you auto attack the tower again, more damage will be dealt this time.

Thank you for reading, I hope this was helpful! Also please buff Riven! Thank you (:

EDIT: I've just noticed this bug doesn't ALWAYS occur, I'll get a video up later today.