Trial Tower + Trial Forest = Dolmen items
Walls of Serdin - Gorgos' Dungeon = Traveller's items and bunny items (These do drop for Lass. I found Traveller's daggers and helm in Kerrie Beach)
Elven Forest + Gorge of Oath = Raider's items.
Marsh of Despair + Forsaken Barrows and POSSIBLY Forgotten City = Meister Clan + White items from bosses.
Forgotten City + Gaikoz's castle = Moonlight items.