It is unclear if this rubbery, spider-like horror is solid, vapor, or some combination of the two.

VAPOR SPAWN CR 8
XP 4,800
NE Large aberration
Init +6; Senses darkvision 60 ft.; Perception +11

DEFENSE
AC 20, touch 11, flat-footed 18 (+2 Dex, +9 natural, -1 size)
hp 102 (12d8 +48)
Fort +10, Ref +8, Will +10

OFFENSE
Speed 30 ft., climb 30 ft.
Melee bite +15 (1d8 +5), 2 slams +12 (1d6 +2)
Special Attacks poisonous vapor

STATISTICS
Str 21 Dex 15 Con 19 Int 10 Wis 14 Cha 5
Base Attack +9; CMB +14; CMD 26
Feats Ability Focus (poisonous vapor), Improved Initiative, Multiattack, Skill Focus (Intimidate), Toughness, Weapon Focus (bite)
Skills Acrobatics +14, Climb +25, Intimidate +18, Perception +14, Stealth +14
Languages Aklo, Common, Undercommon
SQ gaseous form

SPECIAL ABILITIES
Gaseous Form (Su) As a standard action, a vapor spawn can assume gaseous form at will (caster level 5th), but it can remain gaseous indefinitely and has a fly speed of 20 feet with perfect maneuverability.

Poisonous Vapor (Su) Once every 1d4+1 rounds, a vapor spawn can exhale a cloud of noxious gas in a 20 ft. radius. All creatures within the area must succeed on a DC 22 Fortitude save or be nauseated as long as they remain in the cloud plus 1d4 rounds after leaving the area. Creatures must make a new save every round they remain within the area. The cloud persists for 1 minute before dispersing, though a strong wind disperses it immediately. The save is Constitution-based.

ECOLOGY
Environment any underground
Organization solitary or band (2–6)
Treasure standard

The vapor spawn is a malicious, foul-tempered creature that dwells in the Darklands. It makes its lair near other creatures that it can bully into servitude, or offers its services as an assassin to more powerful creatures. Its primary motivation seems to be to spread suffering and pain. It prefers to ambush from unlikely places with its gaseous form ability, and plans its attacks with great cunning.

Art by Matt Spicer