Charybdis

Charybdis (暴風大妖渦) is a gigantic one-eyed mindless blood-thirsty calamity-class Monster, heralded as the Ruler of the Skies. Born from a cloud of Veldora's Magicules, it can be said to be part of Veldora's "family," similar to Rimuru as it is also called to be Veldora's child. As it has no solid sense of self, it operates solely to satisfy its lust for destruction.

Since it is a spiritual life-form it lacks a physical body and thus requires a host for the sake of survival. It is also strongly resistant to magic attacks due to its extra skill "Magic Jamming." As it is originally from the spirit world, it is also accompanied by a couple of Megalodons who are strongly resistant to magic attacks as well. Though Charybdis is said to be a Calamity-class monster, in reality, it is no weaker than a Disaster-class monster (i.e., at the level of a long-time established Demon Lord Seed) since it wields a fraction of Veldora's power. The only reason it hasn't been considered as one is due to its inability of rational thought.

Background
In the distant past, it was sealed by a Hero as it is capable of revival with a given time.

Plot
Moderate Harlequin Alliance members Footman and Tear, under directions from the Demon Lord Clayman, tricked Phobio into becoming the host for Charybdis so that it could inherit his hunger for revenge against the Demon Lord Milim. In the process, the dead dragons supplied by the Majins became additional 13 flying armored sharks that accompany the colossal monster.

Treyni, Trya, and their sister dryad of the Jura Tempest Federation had attempted to stop Charybdis as soon as it entered the Jura Forest but were forced to retreat temporarily due to the immense power and magic jamming abilities of Charybdis. Rimuru Tempest was summoned to respond to the threat, and he decided on an all-out attack on Charybdis by every squad that Tempest has. Additional forces from Dwargon also arrive because Gazel considers it a dangerous situation even for Dwargon, as well as to help out his "junior as king and as Hakurou's student," Rimuru. Milim was left out of the fight on Rimuru's orders, despite her wanting to destroy it herself and her capability to do so.

In the ensuing counterattack, all of the flying sharks were killed via physical attacks, and Charybdis was then attacked directly. However, its magic jamming, ultra-regeneration, and scale swarm attacks made the fight near-impossible to win for the allied forces in that particular interception attack because, as Rimuru later notices, the allied forces didn't use the correct attack methods. Charybdis then mentioned Milim, as the target of its vengeance, which convinced Rimuru to let Milim destroy its physical body but let Phobio's host body out unharmed. Rimuru then extracted Charybdis' magicore from Phobio and isolated it in his own body. It was Charybdis' assault on Tempest and Milim's deductions that led to Rimuru to see Clayman, as well as the other members of the Moderate Harlequin Alliance as an enemy, and Carrion as innocent.

Abilities
Special Skills:
 * Tempest Scales
 * Laser Look

Extra Skills:
 * Gravity Manipulation
 * Magic Sense
 * Magic Jamming
 * Ultraspeed Regeneration

Tolerance:
 * Cancel Pain
 * Resist Melee Attack
 * Resist Paralysis

Trivia

 * Since Charybdis needs a carrier to manifest, it is unknown which were the previous Charybdis recipient/hosts before Phobio.
 * The name Charybdis comes from a sea monster in Greek and Italian myth.
 * Charybdis in all technicalities can be considered as something akin to that of an older sibling to Rimuru Tempest due to him having also been born from the excessive Megicules excreted by Storm Dragon Veldora.