UFF

Hell Plane (Lv. 1) (Unlocked in the beginning)
Encounters: Gremlin, Small Skeleton, Sulphur Elemental.

Small Cave (Lv. 1)
Encounters: Small Skeleton, Giant Rat, Hell Pup.

Cave Extension (Lv. 1-2)
Encounters: Hell Pup, Darkling, Megabat.

Sulphur Reservoir (Lv. 2)
Encounters: Sulphur Elemental, Quill Rat, Mud Golem.

Abandoned Ruins (Lv. 2)
Encounters: Small Skeleton, Crawler, Apparition.

Badlands (Lv. 3)
Encounters: Spine Crawler, Hell Warthog, Carrion Bird.

Cursed Wilderness (Lv. 2-3)
Encounters: Apparition, Hungry Ghost, Small Skeleton.

Molten Island (Lv. 2-4)
Encounters: Sulphur Elemental, Mud Golem, Lesser Ifrit.