NOTE: Credit to this guide goes to user "Nomios" from the forums
If you decide to go with phoenix skills you will obviously want to focus on transformation so you can stay in that form and get better buffs from it. Next, phoenix tempest is an amazing skill for taking out trash mobs. With this, you can activate it when you approach groups, just run through them till they die and deactivate. Phoenix avatar should get one point, or possibly 3, but I would not recommend more than that until end game.
To support these phoenix passives and sustains, you will need direct damage dealers or some sort of defense. I personally prefer the pure damage route so I can do better in boss fights, so I keep kinetic bolt and psychic hammer maxed. I always have psychic hammer equipped due to it being AOE and being able to knockback stun tougher enemies. If you want to just do incredible AOE damage, put points into implosions, you don't even need to be in phoenix form for this to be good, but it doesn't hurt.
The alternative to this pure damage is a much more defensive build using the telepathy tree. You should definitely keep a basic power from telekinesis leveled so you aren't worthless at bosses. I'm not a big fan of slows or fear, but the AOE stun of mind crush is devastating when paired with phoenix tempest. With this, you will basically be invulnerable to trash mobs.
Now skills I want to mention that are just good for any build. Telepathic detection, just a single point, while not a necessity it is extremely nice to be able to view enemies in the minimap and this one point frees up an artifact or medal slot. Next flight, I know some people don't like it, but I absolutely love being able to get through maps faster with this. Not to mention, tempest skills still work while flying, so you can fly, while in phoenix form, doing damage to enemies below you. This combo is extremely useful for soaring through low level areas when doing boss runs. Then finally Rejuvenating Aura, I do not have this yet, but I will most certainly get it. Increased energy regen for your team is always a good thing, and your friends will love you for it.
Also put one point into Rejuvenating Aura, the first point adds 1.5 spirit per second to your nearby teammates, after that the increase per point is minimal or non-existent. That, Flight, Phoenix Avatar, and Phoenix Rebirth are the biggest 1 point wonder skills I've seen. Mind Crush can also be a nice 1 point skill if you find survivability from trash mobs to be a serious issue. As for the ultimate skill, it can be useful for starting a run to fill up your phoenix force without killing things or for initiating boss fights with increased damage for the duration. It isn't really meant to be used as direct damage dealing.
