Kuradal’s Dungeon is located in the Ancient Cavern.  The dungeon entrance is located only through the whirlpool in the lake that goes into Baxtorian Falls.  The only requirement to be able to go to Kuradal’s Dungeon is by completing most of your barbarian training to get into the Ancient Cavern in the first place.  Then after all that you will need to get an assignment from the slayer master Kuradal to be able to enter the Slayer Dungeon. And one more important thing Kuradal is a girl not a guy just to get the name preferences straight.

Here is a picture that will help you locate the slayer monsters in the dungeon:

The Purple are the Greater Demons.  The light purple are the gargoyles.  The blue is the Blue Dragon area.  The red is the Steel Dragon area.  The Yellow is the Iron Dragon area. The pink is the Dark Beasts area. The Green is the Abyssal Demons area. The sky blue is the Hell-hounds area.

Good Luck and have fun Slaying.