Easy Answer

The answer to that riddle is 'Sandragora.' It uses its toxic gas to kill all animals that approach it at night. But during the day, it's simply a plant that deer like to eat. Pretty easy for those of us who like riddles. Anyway, Deathnote didn't know it. Well, I also heard that Shocker only accepts the answer if the actual item is brought to him. So you will have to find Sandragora. You can find it among the roots of shrubs near Glitters at the West end of Silancium. Find the Sandragora and take it to Alchemist Deathnote at the center of the village.

This means we have solved the puzzle, not Deathnote. But... Well anyway, find Sandragora among the shrub roots near Glitters. Then take it to Alchemist Deathnote at the center of the village.

Sandragora! That's what it was. That may have been easy for Peabay, but it was a hard question for me. You didn't know it either, did you?