Level 4: The quest "Gaurdian Sprite Upgrade" appears for the first time.
Level 5: The quest for making friends appears for the first time.
Level 6: The quest for getting a pet appears for the first time. Finish the quest to get your first pet! You also recieve a Broomstick mount in your Level 6 gift pack!
Level 9: By finishing the quest in the Beach Resort, players learn to chat with friends and team up with them! Team up and gain EXP!
Level 10: Players can learn what a mentor is, and how to get one.
Level 12: The quest "Sprite Evolution" appears for the first time, where players can select their classes and skills.
Level 15: Guild-related quest appears.
Level 17: Players can get quests related to Paradise Island, which is a paradise of pets.
Level 20: Class chain quest becomes a daily quest (3 per day) and offers good rewards. There is also "Explore Magic School" quest.
Level 21: There is quest "Play with Pet", where you can go to Paradise Island to upgrade your pet.
Level 23: The quest "Pet Farm" is enabled, an instance where you can upgrade your pet.
Level 24: Players can earn badges, which will give you a stat boost if equipped.
Level 25: Another "Gaurdian Sprite Evolution" quest, to upgrade your sprite and attain new skills!
Level 30: A quest to get an apprentice! There will be surprises for your honor as a mentor. Also, players can accept "Guild Chain quests" which offer a huge amount of EXP. The quests in your Guild base can also improve your strength.
Level 32: A quest to find the traveling merchant, where you can explore the Dragon Cave.
Level 35: There is a quest to challenge The Dark Shrine!
Level 40: Allows your sprite to evolve to phase III to make you stronger!
Level 42: The quest "Irritable Snow Leopard" where you can get Titan Roots, and improve your stats.
Level 45: The quest "Challenge Frost Heart", which offers a different feel to what you originally experienced in previous instances.
Level 50: The quest "The Wilderness", a beautiful and also incredibly different kind of instance.
Level 54: The quest "Challenge Sacred Stone Shrine", which is a slightly more difficult instance! Let it improve you.
Level 55: Your gaurdian sprite may evolve again to phase IV! It will be incredibly strong.
Level 58: The quest "Thorn Quagmire", which is a Boss challenge. Amp up, and kick butt!
(Courtesy of Alfheim Tales Official Guide)