Explorers!
Master Mike realesed a generous document about character options that you can have during your underdark expedition, here the list:
- 2 new fighting Styles: Close Quarters Shooter and Tunnel Fighter
- New Ranger Archetype: Deep Stalker!
- Sorcerous origin: Shadow
- Warlock Patron: The Undying Light
You can download this stuff here:
https://media.wizards.com/2015/downloads/dnd/02_UA_Underdark_Characters.pdf
Gourgeous, no?