Darth Vader couldn't breathe on his own because his lungs and respiratory system were severely scorched and damaged by the superheated air, smoke, and volcanic gases during his duel on Mustafar, leaving him with chronic, severe respiratory failure that required his iconic suit to function as a life-support system, essentially an iron lung, to filter air and help him inhale and exhale.
Because after his battle against Kenobi on Mustafar, Vader was left for dead on the magmatic surface. The intense heat charred his body and as he breathed in the hot air and fumes, it badly damaged his respiratory system beyond all hope.
Health hazards of volcanic fumes
The confrontation results in a near-fatal outcome for Darth Vader who loses several limbs in the fight, and while he is incapacitated on the volcanic shore, he furthermore suffers inhalational injury and third degree burns.
Every time he felt that sense of relief, his dark side connection would weaken because the dark side uses suffering as an ingredient. His experiment in "dark side healing" would collapse, and his lungs would instantly regress back.
George Lucas said Vader was full of anger and hate and desire to avange Padmé on the universe. Suicide or self-punishment wasn't in his mind, not at all, he is raging against the Fates as Lucas put it. Also, he - just like he said to Padmé and later Luke - wants to be an Emperor.
The saddest Star Wars deaths often involve poignant sacrifice, broken relationships, or innocent lives lost, with fan favorites including Kanan Jarrus (heroic sacrifice for his family), Duchess Satine (Obi-Wan's lost love, brutally killed by Maul), Clone Trooper 99 (innocent loyalty and tragic end), Tech (sacrifice for his squad), Padmé Amidala (heartbreak and loss of hope), and Han Solo (fatherly tragedy). These deaths resonate due to their emotional impact, the characters' potential, or the deep impact on other heroes.
Anakin for sure. Obi wan had it hard for sure but he at least had inner peace. Anakin was tormented internally his entire life and externally for the vast majority of it. Philip Thomas true, but in the end Anakin was too ignorant and was easily persuaded to the Dark Side.
The armor's rigid edges rub incessantly against scarred skin, causing burns and sores. Beneath the chest plate and embedded within the metal frame, needles and probes continuously penetrate his skin to monitor and stimulate vital functions, creating unending discomfort.
Vader's suit is basically a bacta tank on crack. Without it, even the force would only be able to sustain him for a short time.  Vader's First Moments in his Suit: Revenge of the Sith Novelization by Matthew Stover . . .
No, Darth Plagueis is not Anakin Skywalker's biological father, but there's a strong theory (especially in Star Wars Legends and early drafts) that his experiments with midi-chlorians to create life led the Force itself to create Anakin, the Chosen One, as a reaction, making Plagueis the "unintentional father" of the prophecy. In current canon, Plagueis is a legend Palpatine uses to lure Anakin, and the exact nature of Anakin's conception by the Force remains a mystery, though he had no conventional father.
To escape the armor's claustrophobic nature, Vader had several pressurized meditation chambers built where he could remove his mask and suit and still survive. Vader longed to be less dependent on his armor and tried at times to function without it, but he labored in vain.
Darth Vader died at age 45 after saving his son from Emperor Palpatine. Severely damaged by Force lightning, he found redemption, became one with the Force, and revealed his true face—portrayed by Sebastian Shaw—before passing.
And the answer is...C) "There is another Skywalker." Star Wars fans might remember Yoda's wise last words to Luke Skywalker in "Return of the Jedi" before the Jedi master becomes a Force ghost.
Vader breaks free of the operating table and takes a few steps before doing the only thing anybody in his position could do, he screams an unholy, bloodcurdling scream. His vocal computer has nothing close to this sound in its database so it translates it to the infamous 'Noooooooooo'.
In Star Wars lore, Order 37 was a grim Clone Trooper contingency plan to capture a wanted individual (often a Jedi) by taking a civilian population hostage, locking down the area, and threatening mass execution if the target wasn't surrendered, making it a horrific tactic used by the Empire to force Jedi compliance. It was considered more brutal than Order 66 because it targeted civilians directly, forcing Jedi to often turn themselves in to save innocent lives, as seen on planets like Bellassa.
Revenge of the Sith
Palpatine explains that Plagueis was so powerful and wise, he had mastered the dark side of the Force to such an extent that he could cheat death (mostly saving people he cared about from death) and create life; unnatural abilities which are unknown to the Jedi.
Darth Nihilus . He is basically a pure dark side being. His mortal form was apparently consumed by his hunger for the dark side of the Force.
Top 5 Most Annoying Characters in The Star Wars Universe