TL;DR:

Exotic Mission Rotator

Weapons entering the playlist will become craftable.
Normal and Legendary Difficulties.
Each mission has a pool of legacy season rewards (armor and craftable weapons) that match the theme of the mission.
Missions with progressive dialogue on repeating the mission will move forward with each run and reset after all dialogue has been played.
Legacy Triumphs cannot be progressed.

Missions:

Presage
    Exotic: Dead Man’s Tale (DMT) craftable w/ new perk pool
    Seasonal Weapons: Season of the Haunted and Opulent Weapons.
    Seasonal Armor: Eidolon Pursuant
    Requires Beyond Light or Season of the Chosen (not Haunted?)
Vox Obscura
    Exotic: Dead Messenger craftable w/ new perk pool
    Seasonal Weapons: Season of the Risen
    Seasonal Armor: Tusked Allegiance
    Requires Witch Queen or Season of the Risen
Operation Seraph’s Shield
    Exotic: Revision Zero (no changes)
    Seasonal Weapons: Seraph Weapons and IKELOS v3 weapons
    Seasonal Armor: Seraph
    Requires Witch Queen or Season of the Seraph

Exotic Crafting:

First completion grants the weapon that can extract the pattern.
Each further completion grants additional intrinsic upgrades (frames).
Each completion of Legendary will award a Catalyst upgrade.

Armor and Weapon Rewards:

Separate weekly rewards for Normal and Legendary.
    One guaranteed deepsight weapon that has not completed its pattern and one armor piece.
    Once all weapons are unlocked a random world drop weapon will drop.
    Additional seasonal weapons rewarded for each completion but no knockout or guaranteed deepsight.
Additional Weekly Challenge rewards:
    One guaranteed deepsight that has not had its pattern completed.
    Armor that you have not acquired for the class you complete it on.
    Once all weapons and armor are acquired then it will drop random drops for both.

Exotic Mission gives bonus progress for Xenology quest from Xur.

Age Gating

To comply with global legislation Bungie will require birth date and country of origin verification on the app, Bungie.net, and when signing in via 3rd party services on the API (light.gg, DIM, etc.)

That’s it for big info on this TWID