Director James Wan will utilize one of Mera's powers in Aquaman that was deleted from the final cut of Justice League. Amber Heard made her debut as the future queen of Atlantis last year in Warner Bros.' big DC team-up, but her role wasn't very big. Like many other characters, her screen time was reduced during post-production, so we didn't get to see her ability to control water.
After Zack Snyder stepped away from Justice League, the movie underwent several changes. On their own, they may not seem too significant to how the movie turned out, but when viewed as a whole there are dozens of changes that were made from Snyder's original version. Some of these differences came down to WB completely removing scenes from the finished product. Jason Momoa's Arthur Curry was a victim of these cuts as his entire backstory was eliminated from Justice League. This included Atlantis set-up, and even Mera's involvement in fighting Steppenwolf during his attack on the underwater city.
Related: Justice League: Every Confirmed Change to Zack Snyder's Version
Mera's role in Justice League is rather small, but she appears in the Mother Box sequence in Atlantis. She takes on Steppenwolf underwater, but the fight was originally much longer. Pre-visualization for a deleted scene from Justice League showed Mera using some different powers against the villain than the movie included. At one point in the extended version of the scene, Mera begins the process of dehydrating him - literally pulling the moisture out of Steppenwolf's body. This same water-bending talent can be seen in the trailer for Aquaman.
The extended trailer for Aquaman showed how Momoa's solo movie plans to harness these dehydration abilities. When Mera and Arthur finally find the ruins of an old Atlantean location, they find a device that is no longer operational. Thanks to a wisecrack from Arthur, Mera figures out that the Atlantean created machine must need water to power it. But, since they are in the middle of a desert, she uses this same technique that Justice League cut. She puts her hand close to Arthur's head and dehydrates him on a much smaller and gentler level. She's able to take beads of sweat from him to get enough water to power the machine.
Even though Mera didn't get to use this part of her powers in Justice League, it is interesting that they would've originally been introduced as a means of violence. Her attempting to rid Steppenwolf completely of water could've killed him if she was able to finish the act. This would've made for a nice contrast to Mera then doing the same move peacefully here, while also showing the incredible control she has on her abilities.
Aquaman started filming well before Justice League hit theaters, so it is unclear when Wan would've found out that the first use of these powers would be cut. Snyder helped Wan by laying the foundation for Atlantis and how the underwater world and characters would be portrayed moving forward. They appear to have been on the same page for the most part - with the air bubble being the biggest exception. Of course, this moment is just scratching the service when it comes to Mera's powers. With Heard's character playing a prominent role in Aquaman, there should be plenty of time for Wan to explore the various ways Mera can control and manipulate the water around her that Justice League didn't have time to highlight.
