My bad dude, after the game that always ulted it stopped ulting, prob something was crashed in that game... About karthus, can you check if turning Q on Last Hit is working? 2 games already and keep last hitting with Q even with it turnned off.
Sorry for troubling you
Karthus was working great for me in URF yesterday. Auto Q was off in clear, than I turned it on and HOLY **** did I push lane and get cs. Went 42/7/12 lol.