Gnosis/Labyrinth of Chaos

One of the Seraphim, fighting closer to her full power.

Reflects Physical Type Attacks.

Absorbs Holy

Biograph
One of the superbosses in the Labyrinth of Chaos, only encountered as a floor 100 boss.

Attacks

 * Attack - One Foe
 * Mouth of Gospel - One Foe (Luka), Pleasure Attribute
 * Hyperion- One Foe, Auto Hit, 3 Turn Cooldown
 * Anti-Particle Rail Gun - All Foes, Auto Hit, Quantum Attribute, 3 Turn Cooldown
 * MLRS - All Foes, Fire Attribute, Burn 10%, 3 Turn Cooldown
 * Wave Cannon- All Foes, Auto Hit, Hadron Attribute, 3 Turn Cooldown
 * Holy Flare - One Foe, Auto Hit, Holy Attribute, Ascension 10%, 3 Turn Cooldown, 18 MP
 * Beam Scythe - Random 5 Foes, Auto Hit, 3 Turn Cooldown
 * All Cancel - All Foes, Auto Hit, Dispel, 5 Turn Cooldown, 6 MP

Strategy
Similar to how Worldbreaker is much harder than Judgment, his counter part, Gnosis is harder to fight than Zion. Despite also being an angel, Gnosis only has one Holy attack, that of Holy Flare. Instead, she uses many Makina skills, while not as dangerous as holy spells most of the time, typically are auto hit and don't cost MP. Therefore, you can not mana drain Gnosis and expect many free turns: She'll lose All Cancel and Holy Flare, but that is all. The rest of her attacks are mostly Physical Auto Hit with 2 exceptions - Wave Cannon and Anti-Particle Railgun, which use Chaos elements instead. If this is your first time encountering them, the gist of it is that these elements bypass Nulls/Absorbs/Reflects of their respective elemental type. For example, 'Hadron' is Wind. If you were to have a member Null Wind (Likely though Cosmic Taoist), Hadron will strike through it. Anyway, the only way to avoid damage is to use a deflector (Through some later super bosses will still damage you through it.) or reach 100% Chaos resist through LoC gear. (Note that you can not see what your current resists are for Chaos type elements.)

Back to fighting Gnosis- She has a rather glaring weakness to Silence and Confusion. However, Silence will only get rid of Holy Flare and All Cancel - moves that can be removed by mana draining, so its useless. Confusion is more useful, as inflicting it, even if she snaps out of it, wastes a turn. With a myriad ways to keep her confused, this fight is a walk in the park. However, take care that you use Magic or Auto Hit type moves when attacking, as she reflects Physical Type Attacks (Basically any Weapon Skills: Sword/Ax/Spear that aren't auto hit.), and absorbs Holy.

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