Rule: Rarity and Complexity

Summary

Rarity denotes many aspects of items and abilities, and how they can be applied. Complexity is exclusively for abilities, and denotes how flexible an ability is.
Rarity is based on a scale, from Basic, to Common, to Uncommon, to Rare, to Exotic, to Legendary and Unique/Artifact. In terms of Difficulty and other metrics, the scale for checks involving such is, respectively, +0, +2, +4, +6, +8, and +10 (for all three of this type).
Simple abilities do exactly what they say without extra fluff, without any extra steps to be effective. Complex abilities do a bit more than simple abilities, but also require a bit more scruples and have much longer rules text. Exotic abilities break convention and, at times, can sometimes break reality, whereas their cost is also great.

Rarity

Basic / +0

Basic items often need no special modifications are easy to produce or reproduce. Unless given another Rarity, all items are considered 'basic', no matter the value (such as a basic gold coin, a basic sword, a basic person, etc).

The Basic Rarity modifier is 0, unless otherwise stated.

Common / +2

A step above basic, but still frequent enough in rarity that it doesn't require much specialty. Whether it is items or creatures, the Common rarity invokes the idea of slight modification, or slight nuance beyond what you'd find in a base model.

The Common Rarity modifier is +2, unless otherwise stated.

Uncommon / +4

Uncommon is a rarity when specialty is needed more than common sense. Both in terms of understanding and usage, things that are uncommon require understanding of the item or creature in order to make sense of such and it's potential origin. In comparison to traditional rarity, this would be considered the "Rare" rarity.

The Uncommon Rarity modifier is +4, unless otherwise stated.

Rare / +6

Rare is what people think of when it comes to the word Rarity. Even if one knows where something should be found, or if something should be normal, it being Rare means that will not always be the case. Rare finds for creatures and items alike need to go beyond specialty, and need a hyperfocus of sorts to understand, or pure luck to comprehend. Traditionally, this tier of rarity is known as "Very Rare".

This Rarity modifier is +6, unless otherwise stated.

Exotic / +8

Exotic is a rarity that comes close to meaning one of a kind. While exoticism applied to people is problematic, Exotic within the confines of the game means something that is shown to exist, but is out of the hands of all except a select lucky few. Exotic creatures are equally one of a kind, thought to be beings of myth. Traditionally, this tier of rarity is known as "Epic", and is often associated with the color purple or orange.

The Exotic Rarity modifier is +8, unless otherwise stated.

Legendary / +10

Legendary is the rarist of the rare, thought only as impractical or impossible. Legendary items cannot be bought or won, and are often found or awarded by some of the most powerful creatures in existence. Likewise, Legendary creatures are often mythological and unknown at their most mundane, and somehow have gone further beyond.

The Legendary Rarity modifier is +10, unless otherwise stated.

Other Rarities

Other Rarities exist, but are often tied to lore and adventure, or have a mitigating factor to highlight their importance.

Artifact

Artifacts are items of ancient, but unknown power. Manhy vary in strength and usefulness, and/or can increase or decrease in potency depending on their user. Unless otherwise stated, Artifacts tend to have +10 modifiers.

Unique

Unique is exactly what it says, there only being one of a kind of said item at any given time. This may be due to a narrative reason (such as a curse), or a balance reason (such as three kobolds in a trenchcoat). Unless otherwise stated, Unique modifiers are +10, like Legendary items.

Complexity

Complexity applies primarily to abilities, and not only denotes rarity, but the strength they may have, and the in-game (or out of game) knowledge needed to use them. It also acts as a mitigating factor for Spellcasters, as more power spellcasters will have easier access to those spells. Conversely, Simple abilities can be used by almost everyone out of the box, which is why all maneuvers and Hybrid Abilities are Simple.

Simple

The most common kind of ability, making up a large swath of spells, all maneuvers, and all Hybrid abilities. Simple abilities don't require any special treatment or knowledge, and can often be used without worry of scaling issues.

For Spellcasters exclusively, most classes with only Simple Spellcasting can only ⤴/Augment Up their spells.

Complex

Complex abilities are almost always spells and sometimes other features (such as some Hybrid Abilities or Unique/Class abilities). Complex spells do a lot, have better/more scaling than simple spells, and can do more for the casters that can wield them. Complex spells are more fanciful, even going as far as to mimic some class features with extra steps. That being said, Complex spells are almost always tools for the corresponding spellcasters, who lack in other ways.

As such, too, Complex Spellcasters can do whatever Simple spellcasters can, as well as ⤵/Augment Down their abilities to use less resources for similar spell effects.

Exotic

Exotic spells are the pinnacle of ability usage, only being available to ability-focused classes after a certain level (except for the Wizard, who gets Exotic spells immediately). Exotic abilities can alter or rewrite reality, dismiss or control who hoards, or turn encounters into a game of save or lose. As such, Exotic spells are also exceeding rare, and only ability focused classes can use them to great effect.