It’s a pretty big deal to be in a film with Cher even if you’re a cast of huge, Oscar-winning stars.

The music icon is the biggest addition to "Mamma Mia! Here We Go Again", playing Ruby, the mother of Donna (Meryl Streep) and the grandmother of Sophie (Amanda Seyfried). Cher only shows up in the final moments of the film but brings down the house singing both “Fernando” and “Super Trouper,” which involves the entire cast, EW says.

Producer Judy Craymer (Mamma Mia!) admits that the finale sequence was a completely surreal experience given the level of star power but the Armenian American diva wowed everyone.

“There was a couple of days when they were all there,” remembers producer Judy Craymer of her starry cast. “I mean there was Meryl and there was Pierce [Brosnan] and there was Colin [Firth] and there was Cher and they had their parents down. Colin had his parents — who apparently had never visited one of his sets — and Pierce had his mother there. It was like our own rock concert really and everyone was completely in awe of Cher.”