Amycus decided to throw caution to the wind and the result of that decision meant completely underestimating Fabian. He already had his wand out when he burst open the back door and was hit with the conjunctivtis curse and immediately felt his eyes start to swell and his vision became blurry.
"AHhh! Alecto!! I can't see!!" He grabbed his eyes with his off hand and sent random curses flying from his wand in the general direction that he thought Fabian's curse had come from.