Heroes of the New Day
With training in this skill, you’re aware of a great many fields of study, as well as a whole lot of information that others might pass off as “trivial” or even “geeky”. Arcana is also used for those who play instruments, as (apparently) reading music and knowing details of pitch and tone fall under the umbrella of all things odd.
Here are a sampling of some of the theories and ideas you likely have heard if you have training in this skill:
The Weave… The prevailing theory that magic across the world is woven into pretty much everything, and that this “weave” overlays all of reality. There are complementary theories about the so-called “Shadow Weave” and “Psychic Weave”… which are either parts of the larger Weave, or simply companion versions that instead cover Shadow and Psychic energy, respectively. You’re also familiar with ideas of different threads in the Weave being imbued with different energies… the power of storms, the power of dragons (see below), the power of chaos, etc.
Dragons… There is a theory that all dragons are somehow connected to the Weave on some base level. Some scholars have theorized that the occasionally observed phenomenon of Draconic racial memory may actually have more to do with the minds of all dragons being somehow connected to the Weave than to any actual inherited knowledge. It has also been posited by some scholars that the first dragons were birthed from the Weave itself (or pulled out of it by Io, the first dragon god).
Stars… Astronomy (and Astrology) both fall under the auspices of the Arcana skill. You’ll know the names of many stars, and potentially be able to learn how to read what they might say about your destiny.
Planes & Demi-Planes… You’re familiar with the general layout of the universe (as accepted by most scholars). The Prime Material Plane is what most people call “the real world” or “the normal world.” Adjacent to that are two demi-planes, the Shadowfell and the Feywild, each of which are detailed on their own pages (or will be soon). The important thing to know, though, is that things that happen in one of those 3 places might echo in the others (especially large, nasty, magical things… see The Great Cataclysm, below). You also know about “the plane above” (aka the Astral Sea) which is where most gods reside, and “the plane below” (aka the Elemental Chaos), which includes sub-domains like the Abyss and the Nine Hells.
Fey Folk & Critters… In addition to telling you about the Feywild itself, training in Arcana will also tell you about the creatures and powers that dwell there, including the Archfey.
The Outlands… In the realm between realms is a strange null-space that has taken the form of a wild and violent desert land known as the Outlands. If an interdimensional portal breaks down (or is improperly cast), it might drop you here. There are warring clans of demons, monsters, angels, and other things that choose to fight in the Outlands simply because it saves having to ravage some place with value. Portions of the former slave races known as the Githyanki and the Githzerai are also said to call this land home, though no one is sure exactly why.
Elementals… Elementals are living embodiments of some elemental aspect of the world (fire, lightning, etc). However, each of these elements also has its own demi-plane, which is tied into the Elemental Chaos (one of the “planes below”). The elemental planes are remnants of the Primordials, who once fought with the Gods for control of all creation. They lost (well, mostly), which is why the Gods are in charge now.
Primordials… You (like many) have heard of the battles between the gods and the primordials at the dawn of time… but unlike most, you know some of the details. You know that some of the less-insane primordials (called the Xel’naga) agreed to leave this reality as long as the gods agreed not to directly interfere with the Prime Material plane. You also know that the rest of the primordials were not destroyed… but rather were “put down” in the next best thing to destruction. So somewhere out there (probably mostly in the Elemental Chaos) are the sleeping, imprisoned, comatose, and/or sliced-up bodies of the primordials. There are frequently crazy arcanists and cultists who think it’s a good idea to try and raise some primordial or other. And it’s people like that who are the reason heroes seldom have quiet retirements.
The Great Cataclysm… While you don’t know what caused it, or even what exactly it was, you are pretty well-versed on the after-effects of the Great Cataclysm. For instance, it did major damage in both the Shadowfell and the Feywild, in addition to wiping out two empires and forever altering the landscape of the Prime Material plane. Great empires and civilizations in both the Shadowfell and the Feywild toppled as a result of the aftershocks from whatever hit the Prime Material Plane to cause the Great Cataclysm. You’ve heard about the Spellplague (see below) and the many strange creatures that are theorized to have come into existence following the Cataclysm.
You’ve probably also heard many of the conflicting theories about what caused the Great Cataclysm. Tieflings will claim that the Dragonborn of Arkhosia tried to force dragon magic into the entirety of the weave, and the backlash caused the Cataclysm. Dragonborn scholars claim that the Tieflings of Bael Turoth tried to tie abyssal energies into the Weave, causing a horrid backlash. One theory states that it was the death of a god (or primordial) on the Prime Material plane that caused the Cataclysm. Another says it was the birth of a god. A great many scholars of Outsiders and Aberrants believe it was the shattering of the Great Crystal Gate that caused the Cataclysm (or vice-versa). Then there’s that joke about putting one bag of holding inside another, and why you should NEVER mix inter-dimensional spaces.
The Spell Plague… One of the nastier results of the Great Cataclysm is known as the Spell Plague. It’s a corruption of the Weave of magic, and it manifests often in a disease-like way in an area. People may get strange spellscars that give them odd magical powers, but also drive them insane. Creatures become stronger, fiercer, and more prone to randomly attacking travelers. Sometimes magic items or arcane spells start acting weird, and other times all magic in an area goes dead. Fortunately these outbreaks are relatively rare, and can be cured by destroying and burning the bodies of all involved. Also they tend to be more frequent in the area around the strange islands known as “The Maze” just west of the Sea of Cataclysm.
The Abyssal Plague… This is a magical disease that turns people into demons. Not 100% of the time, but enough to be a problem. Others just die or get sick for a while before recovering. The illness often evidences itself as coughing, sores over a large portion of the body, and silver & gold veining across the flesh (& in the eyeballs). Other parts vary depending on what kind of demon they’re turning into. Fire often solves this problem, too, though a Heal check might tell you how to treat the disease without nuking the infected.