Leave Sword and Shield Dungeon and the Maku Tree will tell you he has something to give you. Leave Subrosia and teleport to Horon Village. Go see the Maku Tree to recieve the Huge Maku Seed.

Now, warp to the tree in North Horon and go down, left, up, left, up twice, left, up, left, and up. The Maku Seed will emerge and open the Shield of Darkness, and then you'll run into the cane weilding guy, which is actually Twinrova (woops, silly me). She'll split up into Koume and Kotake and leave. Go up twice and enter Onox's Castle.

Go up and kill the Wiizrobes and go up. Note that everytime you head to the left or right for the fairy you will have to use your shield to block the Flying Tiles. When you leave the room you'll return to the first room. This Castle is a gaunlet, so be ready for everything.

The next room has Darknuts and Floormasters, kill them and go up. Kill Facade using Bombs and head of up. Fill up by smashing the pots for the items inside. Now go up and face Onox.

First Form Onox

This Onox is the easy one, thankfully. Hit him with your Spin Attack while dodging the mace. After a few rounds, Onox will sue Din as a shield. Hit Din with the Rod of Seasons and then hit Onox. After two of those he'll dissapear. Head down into the holes that open up to face the real Onox.

This is a toughie. Stand brave, stand tall. You can do it. Ready? Okay.

Whenever Onox slams his hand on the ground, jump on the nad and ride it to the top. Then jump at his face and slash at it. Whenever he launches red fireballs, use the Pegasus Seed and dash around to dodge them. Whenever he launches a blue fireball, jump over and run away from the next one he launches. After 6 hits (with the Red Ring, see the secrets section for how to get it) Onox will die and Din will be saved. Great job, you've won the game... now for the next one...