Lux ULT Gameplay BUG

has a bug that I and the other nine players noticed in a normal game. I was support and had spellthiefs and sightstone when i first observed this. I ulted Amumu, and as my animation was happening, i was flayed. The animation for my ult completed, but no damage was done. I though it was thresh's shield that saved Amumu, but i dont think it can block 350 damage. Second time i noticed this was when i went in to kill JInx. As I ulted and the animation went off, i was hooked (Halfway through the animation). No damage was done. I dont think you can stop the damage from a Lux ult after the animation started happening. The second time this happened I had a spellthiefs and a mejais.