bugs found while playing malzahar, katarina and swain

when i was playing katarina i was still able to ult when the enemy amumu had land an ult on me and it happened through the game. the other is with swain the enemy yasuo turret dived me and killed me but i i cast nevermore on him and the turret kill him but it counted as an execution. the last is with malzahar after casting my ult on the enemy cassiopeia she was still able to cast hers which cancels my ult and she was able to kill me, and in other game i used my ult on the enemy brand yet he was able to use his Q (sear) stunning me and he was able to burst me down and kill me.