The current buffs are definitely a nice push to make them usable. The problem that remains still is that you are merely auto attacking for so much of the rotation. For a phoenix strike assassin to use all synergies, you need to sit there auto attacking for so long.
My suggestion is simple and it doesn’t even nerf or affect other builds that use this tree.
Charging Make it so instead of auto attacking you release the current charge with your auto attack, while building 1 charge. So if you were to use phoenix strike, you use the meteor and build 1 charge. The charges also last longer.
Now for the finishing moves.
Dragon Talon Now spends the same charge multiple times. So if you have charge 3 of claws of thunder, and charge 3 of phoenix strike you will use charge 3 chaos ice bolt, and charge 3 of claws of thunder 3 times. This also gets rid of the redundancy of having more than 3 kicks when maxing it.
Dragon Claw This now spends your maximum charge(s) twice. So charge 3 of claws of thunder and charge 3 of phoenix strike would release 2 chaos ice bolts, and 2 charges of the third claws of thunder.
Dragon flight You can now just teleport freely with it, and you teleport faster with faster increased attack speed.
No buffs to synergies or anything, so it doesn’t affect other builds. Dragon tail is unaffected which is good. It doesn’t need a buff.
Nerfs Finally to compensate for these buffs and to make it harder for assassins to just stack every charge, just revert them back to what they were before LoD released. Fists of fire now requires fists to use. Claws of thunder now requires claws to use. Blades of ice now requires swords to use. Phoenix strike can be used with any weapon as usual.