My only tip is to build a box on a platform saddle quetz with one side open and a gateframe on that side, and trap the Phoenix in there with a gate once it is in. I then use a flamethrower to take it. Hope this helps.
You can get it to spawn next to your base because of the following: It always respawns at it's last location, so if the heatwave ends while you are following it you will know where it is for the next heatwave. It also chases you when you eat flowers... hint hint