This fight will take place just north of the main haven area of Kaanul (the area where the two birds were to help you get back out of this part of the map).
Once you start the battle, you will need to use your upgraded air dash to dodge the spikes as you ride your way up the map to the boss, where you need to strike her to initiate the fight (I used the up + Y technique obtained in Iron Kingdom).
Once you damage the boss enough, she will send you back down to the bottom. Again, avoid the spikes to reach her at the top again (different layout to before). Take more health off and then repeat for a third time.
Once you've virtually finished her off, you'll unlock a new technique to teleport to a binded enemy. Use this and the fight will be over.
Achievement unlocked!