How about zones with no crystals that you have to traverse through to get to a dungeon or instanced fight, similar to Chimera and Hydra at launch. Also make the zones with enemies all +5 levels above you and no warp point or hometown in them. Call them "Barren Zones" as they have been ravaged by the Calamity and no one other than us brave adventurers will venture through them in search of spoils and dangerous bounties.