Mr. 58, also known as the Soul of the Frontier, is the final boss of the Otherworld Tower dungeon, a 50-floor dungeon where players will fight against mobs after mobs on each floor. It is the hardest boss in the Frontier as of the Otherworld Update and is currently known to have one of the highest health pool, damages, and attacks out of any mobs in the game.
Mr.58 is assumed to be the main reason as to why the existence of other mobs is seen in the Frontier in the first place. Mr.58 is also assumed to be the Frontier's magic, an entity or supernatural force that corrupts the creatures of the Frontier from a hidden dimension or realm. Two of these mobs that Mr.58 could have created are the lanterns that were twisted into something dangerous by the Frontier's magic that would soon become the Blue Lantern and the Red Lantern, as implied by the Lantern Mechanism's description. Other examples could include the Pygmy Dragon and the Fantastic Dragon.
As to why Mr.58 is known as Mr.58, it is possible that it came from the mythology where the number 58 is associated with misfortune in many civilizations, particularly the ones native to Central and South America. Due to these civilizations' beliefs of the original 58 sins, the number was symbolized as curses and ill-luck. Aztec oracles supposedly stumbled across the number abnormally before disaster fell.
In appearance, Mr.58 a.k.a. the Soul of the Frontier is seen to be a very bizarre-looking creature symbolizing various elements in Fantastic Frontier. Its main demonic-like body symbolizes the various monsters that roam in the Frontier, and possibly any other places within the Frontier's universe. Its three heads below the main body symbolize the various type of damage types that players have used to defeat the mobs of the Frontier. The three heads of Mr.58 are also the main colors of Fantastic Frontier, red, blue, and yellow. All of these colors are common in the Frontier as the players begin their adventures.
The first head to the left is seen wielding a sword and is red in color with an eyeball near the top of its head. This particular head represents the melee class. As to why red was chosen to be the main color of the melee class, it is assumed that it is used to signify that the color red symbolizes strength and anger (rage), characteristics attributed to the melee class.
The second head in the middle is blue with a mustache and a chimney-like hat with yellow neon diamonds, but can also be seen as a variant of the Fantastic Top Hat. This particular head represents the magic class. As to why blue was chosen to be the main color of the magic class, it is assumed that it is used to signify thought and wisdom, characteristics that are often given to wizards and mages that use magic.
The third head to the right is yellow with two eyes at the end of its 'stalks' coming out of its torso. It also has wings on its head to signify flight, distance, or mobility. It is noted that it also has a massive gun extension from its body. This particular head represents the ranged class. As to why yellow was chosen to be the main color of the ranged class, it is assumed that the color yellow is used to signify some affiliations with money and the use of guns and bows, since unlike the other two classes, the ranged class comes with a cost in terms of ammunition.
Mr.58, also known as the Soul of the Frontier, has the most attacks in the Frontier as of the Otherworld Update. In addition, each head has three attacks whilst the main head has one. It is recommended to have one of the many best armor sets, as well as having at least 600 HP to avoid the risk of getting one-shotted by Mr.58's attacks.
- 3 continuous attacks from left, right, and middle.
- Heavy-damage attack close to the left side of the Magic Head.
- Normal attack close to the left stage sliding across towards the Magic Head.
- A massive laser is cast down onto the middle lane. Players should be aware of the fact that its hitbox is so huge, that it fills the angle of the middle hexagon.
- Spray-like shots are cast from the right, then to the left, then to the right, then to the left. A four-time continuous attack.
- Ice shards appearing out of the ground in order to impale the player(s).
- A rapid-ranged attack from the right lane to the middle stage.
- The ranged head stands still and shoots a multitude of bullets.
- 2 gigantic bullets are summoned, one bullet traveling near the main body and one bullet traveling outside of the main body. The main body is the first and bullets can curve from the outside to the inside.
- A gigantic laser is cast from the left stage all the way to the right. In order for the player(s) to know this attack is coming, an echo-like laugh should echo through the battlefield/fight.
- Mr.58 will attack more frequently when its health goes lower.
- Mr.58 is the final boss of the tower, defeating him for the first time rewards the survivor with The Pommel's Helmet.
- Contrary to popular belief, Hitting multiple heads with a single piercing weapon does not count as all the heads are a single hitbox.
- Mr.58 is highly speculated to be Strangeman. However, there is not much evidence to back up this claim other than the "tree" above Strangeman and below Mr.58.