Artifact EXP
can also be leveled up by using other artifacts or Sanctifying Oils which can be obtained through the Rea that absorb into each other or you can take a short cut and use Sanctifying Oils which can be obtained through the Realm Depot store. Items can reach various levels by absorbing other lower star items into them for example;
Randomized Artifact Boosts
Whenever an artifact is leveled to 4, 8, 12, 15 or 20, its sub stat will get a random boost. For example, the highest critical damage you can get on a five-star item is 7.77% while the lowest you can get is 5.44%.