Cocytus null

“[Earth Bind]!”
—And cast a spell.
Countless chains formed of mud leapt at Cocytus, and Zaryusu broke into a
wild sprint. He had even hidden Frost Pain behind his back so his opponent
would not be able to gauge his attack range.
Shasuryu’s declaration that “I’m almost out of mana,” was merely a ruse to
deceive Cocytus. If he had taken the bait, perhaps he might have been bound by
the mystic chains and been hit by Zaryusu’s charge from behind.
However tough their opponent’s exoskeleton was, he should still be able to
break through if he poured all his strength into the edge. With that in mind,
Zaryusu had abandoned defense to focus on the attack, and the resulting strike
should have been quite strong.
He seems quite confident in his sword.
Cocytus could understand how he felt, because much like him, Cocytus felt
strongly about the weapons he owned. In particular, the sword he now wielded
— which had once been used by his creator — was especially significant to him.
Therefore, despite how lopsided it would make the battle, Cocytus insisted on
doing battle with God-Slaying Emperor Blade in hand, as a sign of his supreme
respect.
However, they had made a miscalculation; which was that their opponent was
Cocytus, Guardian of the Fifth Floor of the Great Underground Tomb of
Nazarick.
“…My. Defenses. Cannot. Be. Breached. By. Someone. Whose. Level. Is. Below.
Mine.”
The chains of mud rebounded off Cocytus an instant before they reached him,
reverting to regular dirt and sinking back into the mire. Low-tier spells could
not pierce Cocytus’s magical defenses.

[...]

And so the blade struck Cocytus’s body — only to deflect lightly off. His body,
which glowed a faint blue, did not have so much as a scratch on it.
This was the result of the impassable gulf that separated the highest-level
NPCs of Nazarick from mere Lizardmen.
“—Forgive. Me. But. I. Possess. A. Skill. Which. Briefly. Negates. Weakly-
Enchanted. Weapon. Attacks. Once. I Activate. It. Your. Attack. Is. Useless.”

- Overlord; Vol 4; Chapter 5