Go to Dune castle. The queen will want to speak to you directly. She'll tell you to speak to the shaman for help on the Terra Spirit and to have 1 of the elder's sons to guide you.
The 4th Hadeed-like son will end up helping you after you've spoken to the Chief. The Shaman in the urn will help you with the spirit. He's the man fishing in the sand. Follow him outside to the warp area and he'll drawthe Terra Spirit but forget the last part. Go see the queen and she'll let you in the fane below the palace to search for clues. The elder's 3 losers will gloat that they found a clue but flee for their lives when attacked by monsters. Save them and they'll give you the King Key. Go back to see the
queen and she'll tell you that it opens up the Sphinx. Go to the Sphinx via the vortex in the village urn.
Here's the deal with the Sphinx: 1-the eyes will shine brightly through the deep darkness. 2-the lips are closed tightly. only time may part them. 3-the ears are born of a broken heart. 4- the nose is in the lowest place and the highest.
It just so happens that under the Sphinx is a giant pyramid you have to explore to get those 4 parts (needed to complete the Terra Spirit). 1-there's a room with 6 coffins in it. Close all 6 to extinguish the light and you'll find 2 gems (eyes).
2-there's a face on a wall further down the line. Stand in front of it and don't move. The lips will eventually open and you can grab the gem.
3-there's a split in the paths further down. 1 leads to the bottom (peak) of the pyramid (4), the other leads to the heart-shaped gem. Break it in 2 and you'll have 2 ears (use the item).
After getting all the pieces, return to the shaman and he'll complete the incantation. The Terra spirit will rid the desert of all monsters and then leave to meet the Flame Spirit.