I'm dropping the Maul Spoiler tags since it's been about a few days. Great interview with Filoni about Vader's mental state.
https://www.starwars.com/news/maul-shadow-lord-season-1-finaleIf you're a practical effects person, this is a fantastic read about them building a model for a ship they didn't have time to CGI
https://www.starwars.com/news/star-wars-maul-shadow-lord-ship-modelAnd Filoni talking to IO9 about Vader's mindset at this point, really good read. He's not the best director, but he knows his SW.
https://gizmodo.com/dave-filonis-philosophy-on-darth-vader-is-chilling-2000754634"The key to Vader for me is that he's not Anakin," Filoni began. "He doesn't recognize that. He can't. Anything that reminds him of Anakin, he's going to destroy. So when he sees a Jedi, he's going to destroy the Jedi, because the Jedi would remind him unconsciously or consciously that he betrayed all of his friends and everything he knew and the life he grew up with. For what? For nothing. He lost everything. He made a bad trade. He was lied to. He was deceived. He can't accept that truth. So he's even farther down the path than Maul."
"Maul is struggling to let go of hate, but Anakin got consumed by it," he continued. "If he were to face what he did, it would destroy him more. I find a lot of pity for him because of what he did and the depth of his treachery. And that's Darth Vader. Anakin's trapped in there somewhere, and Darth Vader won't let him surface. And so to me, the key is not to actually give him a character. He's devoid of it because he doesn't care. Darth Vader does not care. He does not have compassion. He does not see you. He sees the thing he wants to destroy, and he will do that. It's like the same feeling you got in
Rogue One when he comes down the hallway. He doesn't talk to those guys. He's going to destroy them. He has one mission, and all of his remorse and all of his anger and all of his hate is in every swing that he does. That's how it's resolved."
"And [when] he saw Ahsoka, he wants to destroy her," Filoni said. "She, of all people, would remind him of who he was. He's like, 'I gotta destroy that. I can't face that.' Obi-Wan, he wants to destroy him. So he is a destroyer, Darth Vader. And critically, only his son, only his offspring, could make him spark, could make him see something. But at first, selfishly, [he said] 'You and I can rule the galaxy.' That's where he goes. He doesn't come all the way back. It's a long process."