Cave of Wonders Guardian

The Cave of Wonders Guardian appears in Kingdom Hearts and Kingdom Hearts II as an entrance into the Cave of Wonders.

In Kingdom Hearts, Sora, Aladdin, Donald, and Goofy fight it after it was taken over by the Heartless and tries to destroy them. Once they destroy the dark power's source, which is located in his eyes(reached by climbing up its neck), the guardian returns to being an entrance to the Cave of Wonders, and continues to be so throughout the series.

Kingdom Hearts
First, the Cave of Wonders will emit lasers from its eyes, just like the Stealth Sneak did. It can either be reflected (particularly using Guard), or simply avoided. To attack the Cave of Wonders, you need to climb up its side, and then strike it. You do not want to be down where Donald and Goofy are, as the Cave of Wonders will be shooting lasers, exhaling fire and summoning Heartless in the process. If you do not find it easy to climb up the side of the Cave of Wonders, then wait until it dives its head down into the ground. Once this happens, climb up the back of its head. Should you run low on health, you can kill some of the nearby Heartless for some HP Balls. Or, you can go around to the back of the head and try and jump on its back, then run up to the head and attack (this could take some time). Alternatively, if you are good with magic, stand back and lock onto the eyes, using the Fire spell from a distance.

Trivia

 * If you look closely before you defeat the Guardian (or every time you hit the eyes, for that matter), its eyes are filled with darkness.