Long story short: I have an introductory AutoCAD class that is required for the degree I am pursuing. I also use AutoCAD most every day, all day, and have for close to 20 years now. Thus was born:
Cute, ain’t he? It’s like the smoke monster from Lost and Krumm from Ahh! Real Monsters got it on and had themselves an abominable baby boy. Since I went to all the trouble of trying not to fall asleep, I figured I might as well stat the little darling up for Dungeons and Dragons 5th Edition.
Ravenous Cloud
Huge Elemental, neutral
Armor Class 15
Hit Points 130 (20d8+40)
Speed 40 ft., Fly 40 ft. (hover)
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Str 20 (+4) Dex 14 (+2) Con 14 (+2) Int 8 (-1) Wis 16 (+3) Cha 11 (+0)
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Skills Perception +9, Stealth +8
Damage Resistances bludgeoning, piercing, and slashing from nonmagical attacks
Damage Immunities poison
Condition Immunities exhaustion, grappled, paralyzed, petrified, poisoned, prone, restrained, unconscious
Senses darkvision 60 ft., passive Perception 18
Languages Auran, understands Common but doesn’t speak it
Challenge 6 (2,300 XP)
Special Traits:
Cloud Form The ravenous cloud can pass through spaces occupied by other creatures and stop there. Any creature within the cloud’s space has disadvantage on any ability checks and attacks that rely on normal sight. It can also pass through openings as small as 1 inch in diameter.
Actions:
Multiattack The ravenous cloud can make 2 slam attacks and one bite attack on its turn.
Slam: Melee weapon attack, +8 to hit, reach 10 ft, 1 target. Hit: 16 (3d6+6) bludgeoning damage
Bite: Melee weapon attack, +6 to hit, reach 5 ft, 1 target. Hit: 26 (4d8+8) piercing damage
Scan: In place of its slam attacks, the ravenous cloud may scan its surrounding for invisible foes. This acts like see invisibility with a range of 120 feet but only lasts for one round. (Recharge 4-6 on 1d6)
Hailing from the elemental plane of air, ravenous clouds are alpha predators from that windswept realm. On their home plane, their primary prey are invisible stalkers and even when found on the Prime Material they prefer that above other meals. As their name implies, though, ravenous clouds are constantly hungry and will stalk and devour whatever they can.
Unlike invisible stalkers, ravenous clouds are not easily summoned and bound by spellcasters. Sometimes an attempt to summon an air elemental goes awry and a ravenous cloud appears, usually attacking and devouring the summoner. More often these monsters slip through places where the veil is thin between the plane of Elemental Air and the Prime. They are dumb, hungry brutes with whom negotiation in impossible. They can be distracted with prey of their favored sort, however, and are capable of enough low reasoning to be intentionally redirected in that way.
Ravenous clouds are not tactically savvy, choosing enemies seemingly at random but with a strong preference for those that use stealth or invisibility. If there is an invisible stalker within sight of the ravenous cloud’s scan ability, it will attack that enemy regardless of what other threats are present.
I.E. 
