Players can use these data crystals to craft items depending on the capacity of those crystals. Monsters, dungeons, and bosses from YGGDRASIL often dropped loots in form of data crystals. Then we have Artifact items which do not belong to the classifications above since these Artifacts have fixed data. Items in YGGDRASIL are classified as following: Low < Middle < High < Top < Legacy < Relic < Legendary < Divine, with of course, Divine is the most powerful. The Downfall of Castle and Country (Source: Internet) Next, we have more advanced Classes (including bizarre ones) like Cursed Knight, Dark Knight, Holy Knight, Martial Lord, Knight of Niflheim, etc… By combining and unlocking different Races and Classes, players had tremendous amount of choice to build their own character, whether you wanted to become a draconic monk, or a succubus dark knight, or a skeletal lich king. Classes in YGGDRASIL are basically Job Classes like the basic ones such as Warrior, Rogue, and Cleric. According to Overlord Light Novel, there are about 700 races in YGGDRASIL, including more advanced Races which players have to level up their weaker Race to unlock. Each Race also allowed players to gain access into skills and abilities unique to that Race. For example, Momonga (his original character’s name in YGGDRASIL) has: Level 15 Skeleton Mage, Level 10 Elder Lich, Level 5 Overlord, and then 10 more Racial levels which were unknown which Racial level(s) Momonga had. Racial level includes Races which players chose and unlocked.
So why does these sorts of race matter? Well in this game, players can reach the max level of 100, combining between Racial and Class levels. Becoming a Monk Slime? Why not? (Source: Internet)