the slime lure is needed in the sewers where you fight the slime king it is the room beforethe boss' one that will give you a ring wich you will have to take to the blacksmith after you talk to the stranger so you can take out the gem but dont ask me about the reward that the stranger gives you i have it and its... *BIG BAD SPOILER FOR SOME PEOPLE*...armor i think its called arcana something but i tried to equip it on sana, garret, karl, fief and me and nop did not work