The Nun 2 brings back the infamous demon Valak with numerous spine-chilling segments.
Homage to the 'legend' of The Exorcist
Right from the opening scene of The Nun 2, viewers can astutely recognize the film's subtle homage to The Exorcist. As Valak appears and claims the life of Father Noiret, the demonic figure spills out into the nighttime streets and attaches onto a mysterious man, wearing a hat and carrying his toolkit. This character is none other than Frenchie - who had been possessed by Valak since the end of the first installment.

From the setting, nocturnal color palette to Frenchie's portrayal, viewers easily recall Father Merrin's visit to Regan's home to aid her in battling the demonic forces.
Frenchie's haunted journey takes a page from The Blair Witch Project
In addition to The Exorcist, the horror film deemed one of the scariest of all time, The Blair Witch Project also pays its own tribute. In a scene where the delivery girl arrives at the school where Frenchie works, the image of him standing facing the wall, making a terrifying gesture, immediately brings to mind a scene from The Blair Witch Project, when character Mike also stands in a similar manner.

Furthermore, the fate of the delivery girl and the character in the 'Blair Witch' scene, Heather, are alike, as both fall victim to the same malevolent force.
Revisiting the horrific accident in Annabelle
Following the chilling opening scene, The Nun 2 swiftly transitions to the main character, Irene, as she and other nuns attempt to push a stranded car back into motion.

This scene evokes one of the most heart-wrenching segments in Annabelle: Creation, where the character Annabelle Mullins tragically gets into a car accident while her parents' car breaks down, leaving them stranded on the roadside.
Intimidation through Valak's 'distinctive' artwork
Valak is renowned in the Hollywood demon world for its menacing threats through paintings. The Nun 2 continues to employ this method to send shivers down the spines of victims like Irene and Sophie. Some may even recall Pennywise the clown due to Valak's knack for distorting its face unexpectedly.

The Fate of Father Burke
In a scene, Irene is personally visited by the Vatican Pope and tasked with taking over the case of Valak's rampage in Europe. Initially hesitant, she questions whether Father Burke - who stood by her in The Nun - knew about the incident. The Vatican reveals Burke passed away due to an epidemic.

The Warren House Corridor
In a scene where Sophie confronts Valak in a locked prayer room, she witnesses a vision of Valak standing in a familiar corridor.

This is actually Valak's first appearance in The Conjuring 2, at the Warrens' house, discovered by the couple's demonologist daughter. This vision likely hints at Sophie having some mysterious, perhaps even 'blood ties' to the Warren family.
Irene Encounters Lorraine in her Vision
A surprising detail in the future 'prophecy' within The Nun 2 occurs when Irene is briefly overtaken by Valak. She experiences visions, recalling happier times with her mother, and another vision featuring Lorraine Warren.

This indicates a spiritual connection between the 'female exorcists' of The Conjuring Universe - Irene and Lorraine, as well as hinting at the true potential of the Holy Eyes of Saint Lucy which could be utilized in the upcoming film The Conjuring: The Last Rites.
After-Credits Scene Teases The Conjuring 4
The Nun 2 only has a single after-credits segment lasting less than a minute, teasing the return of the Warrens. In their home, Ed receives an unexpected call from Father Gordon. As Ed picks up the phone, Lorraine stands behind him with a curious expression, while Ed quickly asks Gordon about the purpose of the call before the scene ends.

This is undoubtedly a teaser for the next installment of The Conjuring , with the main characters Ed and Lorraine continuing their journey of exorcism. According to IMDb, this film will be titled Last Rites, and David Leslie Johnson-McGoldrick will continue as the screenwriter after The Devil Made Me Do It.