Spoilers ahead for Star Wars: The Last Jedi. In The Last Jedi, Luke Skywalker shocks everyone towards the end of the movie when he sacrifices himself in order to save the Resistance. After spending years in exile on a remote island, Luke shows up to battle the First Order, but just how is Luke with Kylo Ren at the end of The Last Jedi? It isn't quite hand to hand — robotic or otherwise — combat, because Luke uses an astral projection of himself to fight his last battle. It's a good thing, too, because that Luke dopplegänger is able to withstand all of the First Order's weaponry when Kylo Ren orders everyone to shoot at Luke.
After Luke survives the most intense firing squad shooting ever, it becomes clear that the Jedi is using the Force to protect him in some way, but just how is left unsaid. One of the most exciting moments of the movie comes when Kylo Ren gets out of his ship to finish Luke off for himself but fails to do so. Ren cannot kill Luke, and the look on the villain's face when he realizes that his lightsaber went through Skywalker without killing him is a highlight of the movie, not only because seeing Ren look so dismayed is satisfying but because Luke's sheer power is truly incredible to see.
When the movie cuts to the real Luke, hovering above a rock on the island of Ahch-To, you then understand that the Luke that showed up to the Resistance's bunker has simply been a projection used through the Force. Even Luke's heartfelt goodbye to his sister Leia, which was so poignant, has been conjured by the Jedi's mind. That's just how strong Luke's Jedi powers are.
No Star Wars movie has featured this kind of Force mastery before, but a few Star Wars books and comics have used the dopplegänger effect, according to Star Wars' wiki. Through visualization and use of the Force, Luke conjures an avatar of himself that everyone believes was real. The fact that Luke's projected appearance has not been seen before makes it all the more powerful, though. Luke Skywalker is "the last Jedi," and his unparalleled abilities get the grand finale that they deserved. Luke lives up to his legacy as a Jedi master in every way.
The moment when Luke — the real Luke, on Ahch-To — falls out of his meditative position reveals that his wielding of the Force to project such a powerful avatar has used everything he has. Yet while losing Luke is a tragedy for Star Wars fans, it almost makes the new trilogy all the better, as he dies a true Jedi. This means that Rey's attempts to master the Force might not be futile like Skywalker tells her it is towards the beginning of The Last Jedi. Luke's death actually offers a great deal of hope for the Resistance, as he dies in order to save Leia's army, which means that it might have a chance.
Because Han Solo died in The Force Awakens and Carrie Fisher passed away in real life in December 2016, Star Wars fans likely went in to The Last Jedi feeling excited to see Luke Skywalker's big return in the latest film. The fact that he dies in The Last Jedi might seem completely terrible, but it actually is bittersweet. It's undoubtedly sad that the next Star Wars movie most likely will not include Han, Luke, or Leia, but the first two movies of the new Star Wars trilogy have set up an outstanding new generation of characters — both good and bad — to carry on the heroes' legacy.
And besides, Luke dies after using the Force to save the Resistance, which means that it's still worth fighting for. Since Rey also helps the Resistance at the end of The Last Jedi, the movie sets up her role as a great Jedi master, which will likely come into fruition in Episode IX. Perhaps, like Luke, she will find new ways to use the Force to defeat the Dark Side once and for all.