Ainz - Flame Staff

He sent a mental order to his staff to shoot flames—although in this case, “shoot flames” merely meant enveloping itself in them; it wasn’t as if he was attacking with the fire. But Ainz felt the martial king’s eyes shift from him to his weapon.

Yep. You have a troll’s regenerative ability, so it’s only natural that you would be distracted by a weapon that can inflict wounds—via fire or acid—it won’t work on. But that will prove fatal.

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Volume 10, Chapter 3.4