First you need to go to the 1 o clock position on the Paroz Lighthouse map in Ragnarok. Go inside the house and speak with Thor. You need to go to the rogue guild and find a secret passage behind some beds near the guildsman NPC. Speak with Thor's father inside. Go one map east to the 5 o clock position. Walk up to the door and select. Speak with the npc inside.

Head back to Thor and speak with him. He will send you to a place. Head to the sea otter map northwest of Paroz Lighthouse. Go to the hut on the east side of the map on the beach. Walk up to the door and select "Antonio doesn't enjoy destroying upgrade items." Speak with the NPC inside. Now go back to Thor's father. Speak with him and he will approve of your training. Go speak with Thor and he will send you to the training grounds.

You must walk up to the girl as quickly as possible. Once you get let in and you must select left/right/back at random when you catch up to her. There is no trick to stopping her, but a combination of left and right works most of the item Ro zeny. When you finish the test, speak with Thor and he will send you to his father.

At last you can go back to the father in the rogue guild and speak with him about the skill. A "killer" will attack and steal one of his books. You must stop the killer based on what color flashes around him. When it flashes white, you must block left. When it flashes pale yellow, you must block right. When it flashes pale red, you must block his retreat. When you finish this, speak with the father, and he will teach you the skill!