In ET's exclusive sneak peek at Thursday’s all-new episode, mentor Christian Siriano surprises the designers directly after their last runway -- someone even cries out, "Oh god, you’re back!" -- to let them know host Karlie Kloss is waiting for them with a “special guest” on the runway. That guest is Karlie's stylist, Karla Welch, who also dresses A-listers like Sarah Paulson, Justin Bieber and Tracee Ellis Ross.
"I brought Karla here for a reason," Karlie announces to the designers. "In a couple of months, I’m attending a CFDA event in Paris and I need your help creating the perfect look."
The CFDA is the Council of Fashion Designers of America, a non-profit organization focused on developing American design talent through scholarships and other programs. In fact, part of the prize package for Project Runway is a "career-changing mentorship" with the organization.
"This is an amazing, magical moment as a designer," contestant Nancy Volpe-Beringer remarks. "One, it's Karlie. Two, it's in Paris. Three, it's for the CFDA? That's the trifecta."