You were busy dueling with someone trying to kill you but Sebastian came right when you got thrown into a wall because of a spell before you hit the ground and you laid there trying to get up. Sebastian looked at the guy trying to kill you before shouting "I WONT LET HER SUFFER! AVADA KADAVERA!! He shouted as he wand was pointed at the man and the wand began glowing green. Getting the unforgivable curse ready