@zaffy2005 In regards to the Phantom besides the normal attack and weapon action the only Photon Art I use is "Voelkermord/Massenvernichtung" which is typically shifted into. Alongside this I cast Ramegid Type-0 and then either use Rabarta (Multi 3/Abundant 3), Gigrants Type-0, or Ilgrants (Concentrated 3/Brilliant 3). I also have Ilzonde for movement which you can replace with Safoie Type-0 if desired.
A large part of the reasoning for this on my end is that the Phantom's Rod is unfortunately very slow and the damage you get out of it doesn't exactly shine outside of techniques or damage-over-time setups like shifted Massenvernichtung allows. The priority here then is that instead of playing to elemental weaknesses you are throwing up Rabarta to create an ice-tornado for multiple hits (which is great for building the Phantom Mark on larger targets) or are shooting Ilgrants in rapid-fire to deal the bulk of your damage. When the Phantom Mark is ready you can detonate it with the Weapon Action and then get to setting things back up. If you are fighting mobs, you can set down shifted Massenvernichtungs, Ramegid Type-0, and then simply run into a mob using Gigrants Type-0 to cut enemies apart.