The Mana Tower is a relatively straightforward dungeon designed to teach you the ropes. Your main goal in each zone is to locate the Gleamdrop and carry it to the Gleampool. The bottom screen map will show you the general direction and often indicate if the Gleamdrop is hidden (e.g., 'in a vase'). Use your sword's basic attack to destroy pots, grass, and bushes to reveal hidden items and clear paths. Enemies here are basic Rabites and other low-level creatures. Practice your basic attacks and focused attacks. Remember that your HP largely restores between zones, so don't overuse recovery items unless absolutely necessary. After every four zones, you'll have a chance to save and manage your equipment. Ensure you are comfortable with the combat system before reaching the boss.
