WARNING: The following contains major spoilers for The Conjuring: The Devil Made Me Do It, now in theaters and on HBO Max.
One of the biggest things The Conjuring: The Devil Made Me Do It changes from the previous films is producing a credible threat in the onset. Sure, Bathsheba, the Annabelle doll and even the B-plot villains provided potent jump scares and chilling moments. Still, they all were movie trope demons easily exorcised and locked away in the Warrens' museum. However, in The Conjuring 3, as much as director Michael Chaves produces the franchise's most powerful enemy, the film sadly wastes the character's potential.
Isla (aka the Occultist) has studied up on the occult for years. In the final act, audiences discover she became corrupted by these Satanic rituals and relics her priest father, Kastner, kept at home. This turns her into a witch, placing curses on people across America. She's someone not even Lorraine can trace. Sure, Lorraine taps into the Jessica Strong case with her otherworldly vision, but Isla remains hidden in the shadows.
What really scares Lorraine is when she opens up a connection at the morgue. While she spots Isla performing rituals and teasing her, she realizes it's a trap as the gateway can be explored both ways. Thus, Isla can not only transfer her power to the morgue, but she can also infect Lorraine and even Ed if the connection's strong. Luckily, it's cut off in time, but Isla still raises a dead body there to attack the Warrens.
Basically, she's a necromancer, and with her mental powers, she seems to be the perfect equal to Lorraine. This impending battle hypes viewers up. However, The Conjuring 3 doesn't follow through with making her the true antithesis. Kastner ends up selling Isla out, which is done to quickly move the plot along. It would have been better if she'd been mind-controlling him or placed a spell in the former holy man. It'd have shown her ability to rival God's power by monitoring Kastner, especially when the Warrens visited him.
In the film's climax, she infects Ed's mind with a powder after shapeshifting into Lorraine, so this alone could have created a much more cerebral story. She could have hurt Ed or even killed Drew to add real repercussions and mortality to the heroes who always make it out unscathed. Yet, she just has Ed running Lorraine down with a hammer, which ends with him smashing her unattended altar, breaking the curse and taking Isla's power away. It's a bit unbelievable for such a talented villain to not protect the source of her abilities.
Isla's shaped as someone intelligent and conniving, but it just comes off dumb at the end. The Occultist is massively underplayed. Not to mention the fact she doesn't drop eerie lines and threats during her big showdown is pretty underwhelming.
Audiences could have forgiven the lack of proper backstory for Isla getting addicted to demons after being adopted, as her power set is so good. But, ultimately, she just disappears at the end to kill her dad, leaving her chambers vulnerable. This leads to the Devil killing and taking her soul. Overall, it's just too convenient of an ending, ruining what could have been the first villain to really break the Warrens.
Directed by Michael Chaves, The Conjuring: The Devil Made Me Do It stars Patrick Wilson, Vera Farmiga, Ruairi O'Connor, Sarah Catherine Hook and Julian Hilliard. The film is now in theaters and on HBO Max.