Karma is an attribute both in YGGDRASIL the DMMO-RPG and in the New World. Originally, it affected various mechanics in YGGDRASIL, such as influencing the damage of certain spells or abilities , dictating AI actions in certain situations , and dynamically targeted by items  or mid-battle for certain strategies.
In the New World the mechanical aspects still apply, as abilities and items related to karma still work as they did in YGGDRASIL  . One difference is Karma now affects decision making to some extent, though Ainz is an exception to this . The system where karma changes based on actions also still exists .
Karma Categories Edit
Based on the character sheets you can deduce that there are breaks at karma value that separate each rating. This is my attempt at trying to understand it from what we know. I’ll use the current names, but will leave this note. Literally reading the kanji, it might be more appropriate to call them as such:
Extreme Evil(極悪): Literally ’Heinous’, but the prefix kanji can be read as ’very’ or ’extreme’. So depending on the reading it can be ’Very Evil’ or so on. The individual kanji are ’wicked/evil’ and ’evil’.
Great Evil(極悪): Literally ’Wicked’ but as an adjective can mean ’Extremely Bad/evil’, though the two kanji are ’wicked/evil’ and ’evil’.
???? Evil Lupu’s mistranslated Karma Value (凶悪): Literally ’Villainous’/’Fiendish’/’Atrocious’; based on that one line from Enri, I would go with ’Villainous’
Evil (悪): Literally ’Evil’ in some context, but can also be a ’Bad’ when used as an adjective or ’Bad Person’ alone if you read it as ’waru’ instead of ’aku’.
Great Good (極善): ’Very’ ’Good’, but can be read ’extreme’. It’s the same prefix kanji as Ainz’s.
??? Good: Good equivalent of Narberal's karma value.
Extreme Good???: Whatever the +451 and up karma value will be called.
Numerical Breakdown Edit
Extreme Evil (極悪) (-451)— (-500) [-Ainz, Albedo, Demiurge]
Great—Extreme Evil (邪悪～極悪-450) [-Shalltear]
Great Evil (邪悪) -(Y Y Y + 2)—(-449)) [-Neuronist, Solution & Narberal] Where (449) > -(Y Y Y + 2)
???? Evil—Great Evil (凶悪～邪悪) -(Y Y Y + 1) No Data
???? Evil (凶悪) -(1XX + 2)—(-200)—-(Y Y Y )[-Lupu] Where (Y Y Y ) > (200) > (1XX + 2)
Evil—???? Evil (悪～凶悪) -(1XX + 1) [-None; by assuming symmetry should be over (-150) since Yuri;s (+150) is still in the group past Neutral—Good.]
Evil (悪) (-101)—(-1XX) [-None]
Neutral—Evil (中立～悪) (-100) [-Entoma, Mare & Aura]
Neutral (中立) (-99)—(+99) [-Hamsuke, Victim, Krusch, Pe Riyuro, WDL, Gondo, Zenberu, Kyouhukou, PA, etc]
Neutral—Good (中立～善) (+100) [-Zaryusu & Shizu]
Good (善) (+101)—(+1XX) [-Yuri] Where (1XX) > (101)
Good—??? Good (+1XX + 1) [-No data, but assuming symmetry and the above argument for the evil variant]
??? Good (+1XX + 2)—(+200)—(+Y Y Y ) [-No data assuming symmetry, supposedly Remedios] Where (Y Y Y ) > (200) > (1XX + 1)
??? Good—Great Good (Y Y Y + 1)
Great Good (極善) (+Y Y Y + 2)—(+300)—(+449) Where (449) > (Y Y Y + 2)
Great Good—Extreme Good??? (+450) [-No data, assuming symmetry ]
Extreme Good??? (+451)—(+500) [-No data, assuming symmetry]
From the character sheets released, there are four distinct karma categories on Evil side of the karma spectrum. By symmetry we can assume Good categories also exist in equal number, but only two are confirmed with Yuri and Sebas for now. The four Evil Karma categories can be seen on Ainz's character sheet, Narberal's character sheet, Lupusregina's character sheet, and Aura's character sheet. The main English character sheet fails to convey that the kanji on Lupusregina's and Aura's sheet differ. It should be noted that Aura is not a definitive Evil karma character, but is one of the intermediate karma holders. These intermediate karma values are the borders between two karma categories, they include Shalltear, Aura, Mare, Entoma, Zaryusu, and Shizu. The hypothesis of symmetry comes from the fact the 100 karma value on both sides of the spectrum is an intermediate karma value.
- ↑ Volume 13 Chapter 5: [Uriel], on the other hand, was a spell that could be learned by a magic caster of any type as long as the requirements to learn it were met, but it only did its listed damage when cast by a magic caster with a maxed-out positive karma value. Its damage decreased as one’s karma value decreased, and for someone like Ainz, it would do less damage than a first-tier spell.
- ↑ Volume 3 Chapter 3: I’m pretty sure that was what left her standing here by herself, without any orders. However, she will probably defend herself against anyone who gets too close or who attacks her. Most evil-aligned NPCs will do just that, so don’t get too close."
- ↑ Volume 3 Chapter 4: There was "Ahura Mazda", which had a potent effect on anything with a negative karma value, and its area of effect could span an entire world.
- ↑ Manga Supplement 4: Holy Smite: A 7th-Tier spell cast by a Dominion of Authority. Envelops the target in a column of pure light and inflicts massive damage to those with evil karma.
- ↑ Volume 13 Chapter 4: The holy sword glowed with divine radiance, and light extended out to twice the length of the actual blade. This light was apparently more dazzling the more evil a being was. In this state, avoiding or blocking this blow would be more difficult. The word "apparently" because it did not seem that bright to Remedios’ eyes. This guy – he’s not evil-aligned! This move was more effective the more evil one’s foe was. In contrast, it did little damage to non-evil targets. It did practically nothing to good-aligned people. In other words, the fact that it had hurt Vijar meant that he was not good, but it meant he was certainly not evil. He made the people suffer! He invaded our country! How can someone like that not be evil!?
- ↑ Volume 3 Author Thoughts: Karma values largely influence fundamental courses of action, Ainz’s case is an exception. Therefore he can make use of his gentleness.
- ↑ Volume 12 Author Thoughts: Using the skulls of one’s food as ornaments does not penalize one’s karma rating.