WARNING: The following contains spoilers for Star Wars: Darth Vader #14, on sale now from Marvel.
Darth Vader's extreme level of power has given him an enhanced level of infamy as he has spread terror throughout the galaxy. Most opponents attempt to defeat Vader by sending wave after wave of soldiers after him. While Vader has had some one-on-one battles with other lightsaber-wielding foes, his enemies rarely try to use the Force against him. Star Wars: Darth Vader #14, by Greg Pak, Raffaele Ienco, Jason Keith, and VC's Joe Caramagna, just revealed how Force mind tricks affect the Dark Lord of the Sith.
Darth Vader has been at the wrong end of multiple betrayals lately. After getting back in Palpatine's good graces, Vader began a hunt to recover the carbonite slab of Han Solo. This led him into an alliance with Bokku the Hutt but he was ambushed by IG-88 when he followed Bokku's initial lead. IG-88 possessed a device that gave it control over Vader's suit. Vader was able to break free from IG-88's datapad before destroying the droid and tracking the device's origin.
This led him back to Coruscant in Star Wars: Darth Vader #14. Here, he discovered that Sly Moore, one of Palpatine's most trusted advisors, was behind IG-88's attack. Vader attempted to apprehend Moore but was led into a trap where she tried to use the datapad on Vader yet again. This failed as Vader had already fixed the flaw in his suit that gave IG-88 control. With nowhere else to turn, Moore tried to use a Force mind trick on Vader, which proved ineffective. Vader exclaimed that he is a Sith, and thus, she could not bend his will.
While it might seem strange that an untrained Force user believed she could use the Force against Vader, she has had recent success on lesser beings. Most recently, she had been caught by Palpatine's Grand vizier, Mas Amedda, when she was researching Vader's armor. She had been previously demoted and did not retain authorization to view such files. She used the Force mind trick to send Amedda on his way without any memory of the event.
While this is one of the few instances Moore is seen using the Force within the Star Wars canon, she had a deep history with Palpatine in the Legends continuity. The Clone Wars Campaign Guide supplement to the Star Wars Roleplaying Game Saga Edition revealed that Moore actually trained under Palpatine before his ascent to Emperor. She eventually became one of the first to learn that Palpatine and Sidious were the same and pledged undying loyalty to him.
This is one of the first times a Force mind trick was seen performed against another Force-sensitive individual. It's typically only been used countless times on stormtroopers by the likes of Rey, Obi-Wan, and even Ezra Bridger. The most notable use of the mind trick was not performed against a Jedi, but against bounty hunter Cad Bane. In The Clone Wars episode "Children of the Force," Mace Windu, Obi-Wan and Anakin all perform the mind trick at the same time to get Cad Bane to bring them to a Holocron. Cad Bane's will was so strong that it took multiple skilled Jedi to coerce his mind.
While there are species that are immune to the Force mind trick, like Watto's species, the Toydarians or the Hutts, those that possess strong will are also immune. This is why it took multiple Jedi to trick Cad Bane, who is not Force-sensitive whatsoever. It's also believed that if one Force-user tries to mind trick another, a large gap between their abilities is required for the trick to be successful. Nobody besides Palpatine possesses a better understanding of the Force than Vader, which makes him nearly impervious to Force suggestions. Vader's most recent encounter with Sly Moore proves that mind tricks are useless against him.