There are two main types of magic – divine, from the gods, and arcane, from the Weave. Clerics, paladins, rangers, and druids pray for spells and their gods grant them. Arcane spells are for wizards, sorcerers, bards, who have to spend some time studying or practicing to memorize new spells per day. The Weave is how arcane casters interact with magic. By using verbal components, casters simple say things and that activates the threads of the Weave for the desired magical effect. Somatic components require the caster to perform some kind of motion, waving their hands or swaying in a particular way. Some magic, divine or arcane, requires a focus, generally a physical object for the caster to base the spell around. Material components are usually tied to arcane magic, but can be required for some divine magic as well; they are items used up by the spell, like bat guano for a fireball spell, or diamonds for a resurrection spell.
Mythals and elven high magic – Mythals are large, permanent area spells that change some aspect of reality or magic within its bounds. They were first used by circles of elven High Mages. They could exclude certain types of creatures, such as evil dragons. Some control weather conditions, as in Evereska. The ability to create new mythals has been lost.
Dracorage mythal – Created by the elves, this mythal interacted with a comet that appeared over Faerun at certain intervals. When the comet, called the King-Killer Star, was in the sky, dragons would begin to go feral over a period of ten days. They would raid and rampage mindlessly. This mythal no longer exists.
Mythallars – invented by the Netherese, mythallars are similar to mythals – both create a change in the area as to how reality works. Mythallars were generally used to power flying cities of Netheril, and they also allow quasi-magical items to operate; quasimagical items are items that work without needing to be recharged when within range of the mythallar, and are useless outside of it. Mythallars were usually 100 foot diameter spheres of metal or crystal.
Nether Scrolls provide endless magical information. Read them once and learn something. Read it again, and you’ll learn something else, something new. Netheril built its power on the knowledge on these scrolls. The elves of Cormanthyr stole some from Netheril and turned them into trees. The scrolls always reform, they can’t be permanently destroyed.
Spellfire – Basically raw magic. Users can control it to absorb spells, destroy dead magic areas, and regenerate lost hit points. Very powerful. Mystra’s Chosen can generally wield it, as can some random others.
Tears of Selune are hundreds of asteroids that trail after Toril’s moon, Selune. They were created when a bunch of dragons tried to destroy the comet that the dracorage mythal is tied to. They missed and hit the moon. Selune and the Tears are inhabited. They used to be covered in an illusion spell so that people on Faerun couldn’t see the settlements on the moon or in the Tears, but those spells failed during the Spellplague.
Chosen are people who are picked to represent the interests of a god on Faerun. They get special powers for being Chosen. Elminster and the Seven Sisters are all Chosen of Mystra, for example.
Elminster is the Realms’ resident grouchy old wizard, and also borders on all powerful. The goddess of magic was in love with him (or she was, two or three deaths ago). He’s got a spell for every situation, and mostly doesn’t solve everyone’s problems because he doesn’t want to be bothered. Manshoon hates him.
Manshoon is a wizard who established the Zhentarim, has dozens of clones that his spirit can flee to if his body is slain, and fights Elminster constantly. A bunch of Manshoon’s clones once animated all together, and they fought over control of Zhentil Keep because they were all convinced they were the real Manshoon. Eventually, some of them departed to join other organizations – one joined the Night Masks in Westgate and another allied with Halaster in Undermountain.
Seven Sisters are women granted immortality by Mystra and are also her Chosen. They generally help Elminster.
Emerald Enclave – a group of nature lovers, basically. They work to stop threats to the natural world. Very widespread networks, agents usually work alone.
Harpers – kind of a secret society, in that everyone knows about Harpers, but individual members are often unknown. They battle evil, and work to create a new age of peace.
Lords’ Alliance – a loose organization of trade partners in the north, from Waterdeep to Luskan to Neverwinter to Luruar (especially Silverymoon). Partially it was created in response to the growing threat of the Black Network of the Zhentarim, and to prevent the Shadow Thieves of Amn from getting any stronger in the north.
Zhentarim – founded by Manshoon, the Zhentarim are a collection of evil humans who mostly worship Bane, though most began to worship Cyric during the Time of Troubles. Who they worship now is anyone’s guess. The Zhents operate the Black Network, a collection of merchants, traders, spies, and assassins. They undercut their competition, make the local dependent on them, and then take advantage of their monopoly when they are the only place in town. Beholders work with them. They like to threaten the Dalelands.
Cult of the Dragon – necromantic cult dedicated to undead dragons. They convince dragons to become dracoliches, then use the phylacteries to control them. Founded by Sammaster.
Kraken Society – Founded and led by a kraken Chosen of Umberlee, Slarkrethel, the Kraken Society is an information network that operates in the North. They are enemies of the Harpers and the Lords’ Alliance.
Lords of Waterdeep – Most of the Lords actually rule anonymously. One is the Open Lord, the lord who rules publicly. Rarely do the lords gather to make actual rulings, and even when they meet, typically only four gather, one of which is always the Open Lord. The current Open Lord is Laeral Silverhand.
Luruar – a confederation of city-states and kingdoms in the Silver Marches in northern Faerun, brought together to fight the many orcs and other monsters in the area.
People of the Black Blood – Malar-worshipping lycanthropes that move in packs, typically with one leader. They have occasionally communicate with one another, and as the members can appear as normal examples of their race, no one knows how widespread the People are. They typically live in wilderness areas.
Red Wizards – formerly the Red Wizards of Thay, they are now a loose collection of wizard merchants, traveling the land offering magical wares or opening shops in towns. Not all Red Wizards are actual wizards, since the name ‘red wizard’ is like a title now, handed down from parent to child.
Twisted Rune – a secret cabal of liches and other undead spellcasters. They mostly play the waiting game, being essentially immortal, and mostly work through others who may not know they are working for the Twisted Rune.