All options from the PHB, Sword Coast Adventurer's Guide, and Xanathar's are available to players. In addition, options from PotA itself are added and can be seen in this PDF: Elemental_Evil_Players_Companion_(5e).pdf. The Aarakocra are banned, because fuck giving out free fly speed. Note that the spells in that PDF are all in Xanathar's, so there's no need to look at them separately.
Characters should be generally good aligned or at least willing to work towards good goals. Some inter-character friction may occur but I would prefer the game not turn into a PVP-fest.
PHB 165: Feats
XGE 77: Rate of Falling/Flying and Falling. As PotA will, at minimum, have air elementals, it seemed worth expanding the base falling rules.
XGE 77: Sleep. This expands the rules for waking someone up, sleeping in armor, and going without sleep.
XGE 78: Adamantine Weapons. I don't really know why we'd care, but why not.
XGE 78: Tying Knots. Why knot?
XGE 78: Tool Proficiencies. As I am yet to see a situation where we've cared about having a tool proficiency, and I certainly wouldn't take one over a skill proficiency, there will be benefits to trying something for which you have both a relevant skill and tool.
XGE 85: Identifying a spell. Allows you to as an action or reaction identify a spell previously cast, or as a reaction identify a spell being cast. NOTE: Since both this and Counterspell use your reaction, you don't have time to figure out what spell is being cast before you counter it!
The Lucky feat is modified thusly: If you use it while you have disadvantage, roll two dice and choose one.
Each player is encouraged to choose one of the following hooks. No two characters should choose the same hook. Additional information will be given once it is chosen, unless it is more open ended, in which case details can be invented collaboratively between players and GM.
Five factions are available for play in this campaign. Faction membership can lead to new sources of information and favors and opportunities for advancement within your faction. However, you may also be expected to take on jobs that further the goals of your faction. You may start the campaign already a member of one of these factions, or you may join a faction through roleplay during the campaign. Joining a faction is optional and players who do not belong to a faction will not be penalized.
The factions are the Harpers, the Lord's Alliance, the Order of the Gauntlet, the Emerald Enclave, and the Zhentarim. More information about each faction can be found in the Sword Coast Adventurer's Guide on page 147.
Feel free to pile this on with the "Faction Agent" background, but by no means feel obligated to.