Yeah Crunch Time! Thats a very great Article and with so much stuff in it! 8D
The Ideas are great but some things seems a bit wonky at the moment:
* Close Quarter Shooter: This adds advantages from two great Feats and add a +1 to Attack. While I really like that Style, it seems a bit to strong at the moment (except if you plan to take those feats)
* Tunnel Fighter: I'm all for defender-styles! It's a bit strange to have to use a bonus action for the stance which allow you to make opportunity attacks without reaction, but still having to use reaction for attacks if the enemy moves without leaving your reach.
* Ranger - Deep Stalker: Seems a bit weak for me. The Underdark Scout is great in the first round, but then useless if you don't have the right terrain or if you are a melee fighter. Stalkers Flurry is nice, but still limits you to 2 successful Attacks per Round, which is simply weaker than the Fighters 3rd Attack or some other Ranger Options (Animal Attacks twice,..).
* Sorcerer - Shadow: Casting Darkness with 1 Sorcery Point and seeing through it and much higher survival Rate with Strength of the Grave seems quite strong. Overall strong but very cool! The first Sorcerer that I would play, even without any bonus Spells.
* Warlock - Undying Light: I don't like the Expanded Spell List .. I miss either Fireball/Scorching Ray, which are the Archetypical Firespells (a light Cleric is still the better blaster then this Warlock) or a Healing Spell for the positive Plane Conection. But all the other Feature are awesome. 8D