Sand

Sand is a Venus Utility Psynergy learned by Felix at Gaia Rock during Golden Sun: The Lost Age. It costs two Psynergy Points to cast.

Felix must be standing on sandy ground in order to be able to cast Sand. When cast, Sand dissolves Felix (and, by extension, the rest of his party) into the sand beneath him. In this state, Felix can burrow beneath obstacles, including walls, and travel up or down "sand waterfalls". It is used extensively in the Ankohl Ruins, among other locations, and is needed to reach the Yampi Desert Cave.

Sand is learned from a tablet that appears deep within Gaia Rock, after the Serpent is defeated. In theory, any Venus Adept, including Isaac, should be able to learn Sand. However, Felix is the only playable character to acquire Sand.

The King Scorpion, the boss of Yampi Desert, is able to burrow under the sand in a similar manner, although it likely doesn't actually know the Sand Psynergy. It does, however, use the same exact field visual as when Felix uses the Sand Psynergy.

Sand can also be used on the overworld map, on beaches, and surprisingly enough, roads too. Since a portion of sand around the south-western entrance of Yampi Desert can be walked on without entering the desert, Sand can be used to traverse the overworld of the desert. Pressing A will make Felix take his standard form again, allowing complete free roam inside the desert, but obviously, upon any attempted exit, Felix will instead appear at the corresponding entrance to the actual Yampi Desert.