Well, Mana Egg Fusion has to be one of the most important neccessities in Grandia III, to boost your elemental attacks, and to gain the ability to use higher-level magic spells, by extracting from the Mana Egg. Until you get the Legendary Thief Skill, your ability and the chance to find high level eggs will not have been as good enough. Despite the ability to obtain most eggs, you can create from the first four level one eggs, any other mana eggs. Each egg and to create a combination will require farming.