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

You can look for it with a parasaur when heatwave isn active...it can detect an ash pile...i got lucky and found one after 5min

Find a phenix during a heatwave and follow it until it ends. The phenix will turn into ashes and land on the ground but will spawn right back at the same exact spot during the next heatwave. Build a trap 6 blocks high so I can't glitch out and you have yourself a trapped phenix to tame:)

You can use the wynern to breath fire on it and follow it round during the heatwave it makes easier to trame without using a random flyar and hit it with a trouch