Shaco Ult Bug (Gameplay)

I was playing a summoners rift game one day and I was playing shaco. During this game twice I ulted when fighting a darius to avoid his q. Both times his q hit me regardless of my ulty. One of the occasions I ulted inside of his q where he should not heal, causing him to heal from two champs even though it did not hit me. Of course you can recreate this by having a darius q a shaco who ults at the same time.