After the lunar eclipse passed, Jennifer put herself in a protective circle that Scott hadn't been able to penetrate before. Nevertheless, he tried again. “You've tried this before, Scott. I don't remember you having much success," Jennifer said confidently.
As Scott pushed, though, his eyes turned from yellow to red, marking him as a "True Alpha." He was able to break through her protective field, rendering her vulnerable. E! Online's Tierney Bricker gave the show a shout-out for the special effects used in that sequence.
Scott then told Jennifer he didn't care what color his eyes turned. He intended to kill her. But Deucalion took that honor, as his eyes are already the color of someone who has killed.