Spirits of Rage (info, skills, hints and etc.) *may include SPOILERS*

[Imperial Dane]

The Plugen quest is the first quest you are given right after you come out of the Knight's Temple, it's the quest for the king, collect the blue squares with a crown on them and defeat the robber, then return and you are given a rage chest with a few spirits already ready, although it won't be like this in the full version where you will have to do quests for the spirits before you can use them.