Then travel to the Sochen Cave Palace, and go through the Ascetic Door. Give the Dragon Scale to the Wyrm Philosopher, and in return, you'll get the Ageworn Key. Then travel to the Northward area of the Cerobi Steppe and find Windmill #10. Start off by completing Hunt 21: Get My Stuff Back! (Vyraal - Rank V). You should have a Dragon Scale in your Important Items. Try and get three White Masks (I found one, weirdly, to be enough) to make the fight easier. You want to be at least level 70 to tackle Hell Wyrm, and there are a few things you need to do before you can get to him. There will be the assumption that you've already opened the Ascetic Door, and that you have access to all of the Magicks and Technicks in the game. Hell Wyrm - Sochen Cave Palace - Hall of the Wroth God Head to the Corridor of Sand, and just before entering the Wyrm's Nest, prepare your party with any buffs you have (Protect etc.) and prepare yourself for a battle. This will allow you to get to the Wyrm's Nest. Now you're able to fight the Earth Tyrant. Speak to Rizmat, and Northon will give you the Windvane key item. You'll find Rimzat, Cotze, and Northon together at the Westgate. Head to the Windtrace Dunes, via the Shimmering Horizons. Search the Dynast-Cactuses on the southern wall to find the Wind Globe. Head back to Rabanastre.
He'll tell you that you need to find his half of the Windvane that's buried under a Dynast-Cactus in the Westersand. You'll then need to go to Lowtown's Northern Sprawl and find a man called Northon. He's sitting on the floor, next to a red Bangaa, just south of the entrance to Garamsythe Waterway. Find a man sitting on the fountain called Cotze. Agree to help him and then head to the Southern Plaza. Start off by going to Rabanastre's West Gate, and look for a Bangaa called Rimzat. There's a whole side quest that needs to be completed in order to fight the Earth Tyrant.