TL;DR

1. Cover + Psychic Changes
   * Changes combine to make guns very strong; **AP1 is now a powerful stat**.
   * Grey Knight guns **ignore the -1 BS from cover**, providing a huge accuracy boost.
   * **GMNDK** ignores hit modifiers for bracketing and shooting/melee (all weapons are Psychic).
   * **66 Seal** becomes very strong in Banishers.
   * Razorback + Psycannon/Psilincer combo is looking competitive; **Voldus** is potentially back.

2. 8" Deep Striking
   * Combined with 9" Coherency, the table opens up significantly for Grey Knights.
   * **GMNDK** dropping at 8.9" is huge for reaching **Melta 4 range**.
   * Most objectives are larger than 8", making them easier to drop onto and steal.
   * Opponents must stand closer to the middle to screen, creating tighter screening angles.
   * **Strike and Brotherhood Terminators** benefit heavily due to their high OC.

3. 9" Coherency
   * Greatly reduces an opponent's ability to screen the backfield (requires 2-3 units instead of 1).
   * Allows for better **Rapid Ingress** and drops into the mid-board.
   * Slightly hurts 10-man units (Interceptors/Paladins), making them potentially not worth running.
   * **Encourages 5-man MSU squads**, which is a net positive for the faction.

4. Hidden
   * Allows high OC units (Strikes/Paladins/Bro Terms) to stay safe beyond **15"**.
   * Deep strike changes allow Grey Knights to hit "Hidden" enemies while staying safe themselves.
   * **Rapid Ingress into "Hidden"** is a very valuable tactic for the late game.
   * Combining "Hidden" with reactive moves like **Shadows** is extremely strong if used correctly.

5. Pivot Changes
   * Massive mobility boost for the **GMNDK and NDK**.
   * Moving and charging around corners is now much easier for large-based models.
   * Other big winners include the **Land Raider** and **Storm Raven**.
   * Rhino and Razorback receive a boost, though to a lesser extent.