Instructions
Defeat the geozard as soon as you reach the sixth floor. The geozard is heavily shielded in the front, so you must attack him from behind to minimize damage to Link. Use the phantom to attack the geozard from behind, then when the geozard turns to attack the phantom, position Link to attack the geozard from behind. Continue the process of switching between Link and the phantom to destroy the geozard.
Walk to the southwest portion of the map.
Block the flame that shoots across the hallway by sending the phantom into it. The phantom will block the fire, and Link can walk past the flame without taking damage.
Walk to the north, and climb the staircase that leads to a higher platform.
Defeat the miniblin. The miniblin will be on top of a statue and Link cannot reach it. Have Link hop on top of the phantom to become eye level with the miniblin. Use Link's sword to kill the miniblin.
Walk to the south end of the room.
Hop onto the phantom to get past three more fire traps blocking the path. The fire traps are low and cannot hit Link when he is on the phantom. The second trap is high enough to hit Link, but it turns on and off. Time the fire trap; when it disappears, run past it.
Walk up to the platform and use Link's whirlwind ability to knock the key from the platform.
Pick up the key. Get past two more flame traps, and use the key on the door to get to the seventh floor.