If the level of the person who made the greatest contribution is higher than the level of the raid monster by 3 or more levels, then the probability of dropping an item or adena will decrease. If the level difference is nine or more levels, then, the monster will not drop any item or adena.
Raid Boss - Level 55
Treant Guardian protecting the outskirts of the forest at command of Enchanted Forest Queen Timiniel. He hates intruders disrupting peace in the forest, and never forgives anyone who violates the Forest Law. With the power given by Queen Timiniel, he summons Sylphs and Unicorns, and protects the Enchanted Forest.