King's Powers From The Seven Deadly Sins Explained
One of the things that sets "The Seven Deadly Sins" apart from most other anime series is the fact that, rather than having a clear-cut main character, the series focuses on seven different protagonists. The titular "Seven Deadly Sins" are a band of 7 extremely powerful Holy Knights within the Kingdom of Liones, who were framed for the murder of Zaratas, The Great Holy Knight, prior to the beginning of the series. In addition, each member of the group has been judged guilty of a hideous crime by the King of Liones, and each one has been given a specific title relating to their "sin."
As such, while these seven knights may be the heroes of the story, they are initially branded as criminals and despised throughout the land, and it doesn't help that most of them are incredibly cruel and dangerous to boot. Every member of the Seven Deadly Sins has a unique set of powers and abilities, and — since most of them aren't even human — almost every member of the team has some form of immortality, or at least an increased lifespan.
Take King, for example, the team's "Sin of Sloth." He is over 1,300 years old, and he wields a specific set of abilities that only a Fairy King can use.
King's fairy abilities give him control over life and death
King's real name is Fairy King Harlequin, and — in addition to being a member of The Seven Deadly Sins — he serves as the protector of the Fairy Realm. Since he is a fairy, King has several unique powers such as levitation, transformation (allowing him to change his appearance at will) and heart reading (which essentially allows him to read the minds and emotions of others), and in addition, his role as King Harlequin gives him the ability to wield a power known as "Disaster." Disaster is an ability granted only to those fairies who are given the title of Fairy King, and it gives the user complete authority to rule the Fairy Kingdom (via The Seven Deadly Sins wiki).
Disaster allows King to manipulate living matter at a molecular level, and essentially gives him complete control over life and death. In battle, we hsave seen him use Disaster to turn a small scratch on his opponent into a massive bloody wound, and also to turn a weak poison into a hyper-lethal venom. Outside of battle, the ability allows him to control the growth and life of nature, granting life to various kinds of flora or ripping it away whenever he likes. The possibilities of the Disaster ability are near endless, though most often King simply uses it to unleash the true power of his Sacred Treasure: Chastiefol.
King can change the form of Chastiefol at will
Each member of the Seven Deadly Sins has a powerful magical weapon granted to them by the King of Liones when the group was first formed, and these weapons are known as the Sacred Treasures. King's is the Spirit Spear Chastiefol, which was forged from the wood of the Sacred Tree that resides at the center of the Fairy King's Forest. King's Disaster ability allows him to change the form of Chastiefol at will, and the spear has ten different forms to choose from (via The Seven Deadly Sins wiki). A few of the more unique forms it may take include a stuffed bear that can parry an enemy's attacks, a crab-like pincer that turns whoever it touches into a fossilized statue, or a giant flower that shoots destructive projectiles at King's enemies.
Chastiefol grows even more powerful when King draws out its "True Form," which activates the full power of the Sacred Tree at great physical harm to King himself. The true form essentially presents the same 10 forms (or techniques) as the regular form, but at extreme power levels. Things get even more complicated after King fully develops his fairy wings, which allows him to wield up to four different forms of Chastiefol at once. With how many attack forms he can combine or use simultaneously, and the near-infinite possibilities his Disaster ability presents, it seems that the only real limitation to King's power is, quite frankly, his own imagination.