Marcellus/Labyrinth of Chaos

Monster Lord Slayer (魔王殺し, Maō Koroshi) is Luka’s father, who is travelling the worlds and killing Monster Lords in an attempt to save the world(s). He has aged hundreds of years, and is only alive due to the Makina he has augmented himself with.

---

Special Abilities: Reflects Physical Element, Applies 200% damage when using Youma/Doll/Chimera Slayer Skills.

Human/Doll Slayer skills are 150% effective.

Biography
One of the super bosses in the Labyrinth of Chaos. He’s randomly encountered in the Hades bonus floor or as a floor-100 super boss, after encountering the Hades Floor six times.

Unlike the rest of the super bosses encountered on the Hades floor, Monster Lord Slayer doesn’t appear when Luka and the party go up to the light; White Rabbit will state that perhaps the boss isn’t coming. However, if she’s talked to, before being able to heal you, Marcellus appears and decapitates her, and confronts the party. Amongst other things, he claims that he’s over 500 years old, and has extended his lifespan by augmenting his body with various Makina, in order to keep traveling between worlds. He states that the cause of the world(s) being destroyed involves Alice being led by White Rabbit, but does not explain further.

(Note: If you talk to White Rabbit at any point, even before approaching the light, Monster Lord Slayer can appear, forcing you into a battle.)

Upon defeating him, he praises Luka for his strength and vanishes.

Attacks

 * Dimensional Severance – All Foes, Auto Hit, Physical/Untyped Attribute, Ignore Deflectors, Dispel, 3 Turn Cooldown
 * Quanta Saber – Random 5 Foes, Auto Hit, Ice/Quantum Attribute, 3 Turn Cooldown
 * Anti-Particle Railgun – All Foes, Auto Hit, Quantum Attribute, 3 Turn Cooldown
 * Wave Cannon – All Foes, Auto Hit, Hadron Attribute, 3 Turn Cooldown
 * Ragnarok – All Foes, Auto Hit, Nuclear Damage, 3 Turn Cooldown
 * Shadow Messiah – All Foes, Auto Hit, Dark Attribute, Death 10%, 10 MP, 3 Turn Cooldown
 * Monster Lord Slayer's Slash – All Foes, Physical, Yoma Slayer, 3 Turn Cooldown
 * Creation Buster – All Foes, Auto Hit, Doll/Chimera Slayer, Imbue Chimera Slayer for 5 Turns, 3 Turn Cooldown

Strategy
A step up from other fights, Monster Lord Slayer isn’t fooling around one bit. His most dangerous attack is the one that killed White Rabbit, “Dimensional Severance”. Barriers such as Electromagnetic Armour and Victorious Clara are ignored, and your buffs are dispelled. While Physical-type nullification (Waning Moon Dance) will protect you from damage, it’ll be dispelled.

His other dangerous attacks are chaos element and auto-hit Makina skills. Of these, “Ragnarok” and “Anti-Particle Railgun” hit the entire party, and “Quanta Sabre” hits 5 times.

Marcellus also completely reflects all Physical-type damage, and actually nulls both Physical-element and Pleasure damage. Since most weapons add Physical-element when their corresponding skill is used, this means that, without Chaos-element attacks, you must use Magic-type and auto-hit attacks. He is also immune to Dark, which comes in handy when slaying Monster Lords.

Marcellus is also immune to status effects, barring Slow. But with a 6.25% infliction rate, the fact that Marcellus’ attacks are auto-hit, and his 0% evasion rate, it’s hardly useful.

While his attacks are very powerful, you are relatively safe from a quick loss, unlike against World Breaker. Take advantage of the fact that he cannot reliably one-shot (or “one-turn kill”) a character that has defensive abilities available (Endure and Auto-Revive).

The easiest way to defeat Marcellus is with a party of Nightmares, as he has no way to damage them.

---Useful Abilities---


 * Physical-type Nullification – Waning Moon Dance grants Physical-type nullification for 2 turns, granting immunity to “Monster Lord Slayer’s Slash”, and protecting you from “Dimensional Severance” damage.

If you do not have Physical-type nullification and need to buff character(s), keep them in the back line when “Dimensional Severance” is available.


 * 2-hit barriers – ALL of Monster Lord Slayer’s attacks are party-wide, but apart from “Quanta Sabre”, they only hit each party member once. Getting up barriers is very important for this fight, as when Dimensional Severance is on cooldown, and especially when Super Appeal/Super Hide is active, you can ensure that a character you are trying to buff is very safe.

---

Check here and here for detailed information on all the super bosses and everything you can make use of to defeat them.