Krobus always sells Void Essence and Solar Essence, as well as one Stardrop. In addition he will also sell one other random item every day. The Iridium Sprinkler is always sold on fridays.
+
Krobus always sells Void Essence and Solar Essence, as well as one Stardrop, one Crystal Floor Recipie, and one Wicked Statue Recipe. In addition he will also sell one other random item every day, except for friday, when he will sell the Iridium Sprinkler instead.