Minstrel Quest - Prontera - Leonard Knox

Each quest requires you three steps.

1. Give the initial item to the NPC.
2. Kill 300 of the monster specified.
3. Give the second item to the NPC.

After which, you will finish the quest and unlock items / equipments.

Quest Name: Hollgrehenn 

Initial Item - 1 Blue Gemstone

Kill 300 Willow

Second Item - 30 Rotten Bandage

Item Unlock: Healing Staff [1] Recipe

Quest Name: Ysmir

Initial Item - 1 Leaf of Yggdrasil

Kill 300 Rocker

Second Item - 30 Feather

Item Unlock: Deathcat Shoes Recipe

Quest Name: Kebak

Initial Item - 5 Fly Wing

Kill 300 Yoyo

Second Item - 30 Jelopy

Item Unlock: Toy Factory: Trick Wand-Marin