BUG ON ASCENSION MODE 23/05/2017

It happened that i was playing an ascension game and that there was a Karthus on the enemy team, he repeatedly was trying to kill the xerath located in the center (everything normal till here). But the bug came in when after dying, karthus was still remaining on the center and could actually still get ascended (still normal? i guess...), which after several trials made him unkillable, he was not receiving ANY damage, but what's even worse is that the player was totally aware of it and was using that bug to his profit, making fun of the enemy team and bragging about it, he knew that that was going to happen. There's the link to the game info, hope you'll fix it soon Riot. (the bug only happens if karthus is dead while ascended)