Margomill is the boss of the House of Gales, a large, multi-eyed creature that spins rapidly. The battle takes place on a circular platform with strong wind currents. The Hookshot is absolutely essential for this fight. Make sure it's rented and assigned to an item button.
Phase 1: Spinning Eye
Margomill will spin around the arena, occasionally stopping to reveal its large central eye. When it stops, quickly use your Hookshot to latch onto its eye. This will pull Link towards it, allowing you to strike the eye with your sword. After a few hits, it will retract its eye and resume spinning. Be careful not to get too close while it's spinning, as it can knock you back. The wind currents can also push you around, so maintain your footing.
Phase 2: Smaller & Faster
As you damage Margomill, it will shed layers, becoming smaller and increasing its spinning speed. The wind currents will also become more erratic and powerful, making it harder to approach. The strategy remains the same: wait for it to stop and reveal its eye, then use the Hookshot to close the distance and attack with your sword. Timing becomes more critical in this phase due to its increased speed and the stronger winds. Dodge its charges and keep an eye on the wind direction. Defeating Margomill rescues Rosso and grants you the Pendant of Wisdom.