The oasis appears as an idyllic desert respite, offering water, shade, and even perhaps edible fruit and nuts in the trees above.

Mockmire. The oozasis, or oasis ooze, is also known as a mockmire in other climates. It mimics a peaceful, pristine watering hole to draw in unsuspecting prey. An oozasis cycles seemingly at random between wakefulness and hibernation.

Quest Givers. Within its odd physiology stirs an ancient mind with an inscrutable purpose. Far from being a mere mindless sludge, its fractured intelligence occasionally awakens to read the thoughts of visitors. At these times, it tries to coerce them into undertaking quests for cryptic reasons.

Ancient Minds. Some tales claim these creatures preserve the memories of mad wizards from dead empires, or that they have unimaginably ancient, inhuman origins.

Oozasis

Gargantuan ooze, unaligned
Armor Class 7
Hit Points 217 (14d20 + 70)
Speed 20 ft., climb 20 ft., swim 20 ft.

STR	DEX	CON	INT	WIS	CHA
18 (+4)	5 (-3)	20 (+5)	12 (+1)	22 (+6)	18 (+4)

Saving Throws Int +5, Wis +10, Cha +8
Skills Deception +8, History +5, Insight +10, Perception +10
Damage Vulnerabilities thunder
Damage Resistances fire, lightning; bludgeoning, piercing, and slashing from nonmagical weapons
Damage Immunities acid
Condition Immunities blinded, charmed, deafened, exhaustion, frightened, prone
Senses blindsight 60 ft. (blind beyond this radius), tremorsense 120 ft., passive Perception 20
Languages understands all languages but can’t speak, telepathy 120 ft.
Challenge 9 (5,000 XP)

Amorphous. The oozasis can move through a space as narrow as 1 inch wide without squeezing.

Mirage. As a bonus action, the oozasis can create a mirage around itself to lure victims toward it while disguising its true nature. This functions as the mirage arcane spell (save DC 16) but is nonmagical, and therefore can’t be detected using detect magic or similar magic, and can’t be dispelled.

Waters of Unfathomable Compulsion. Any creature that drinks the water of an oozasis or eats fruit from the plants growing in it has a dream (as the spell, save DC 16) the next time it sleeps. In this dream, the oozasis places a compulsion to carry out some activity as a torrent of images and sensations. When the creature awakens, it is affected by a geas spell (save DC 16, cast as a 7th-level spell) in addition to the effects of dream.

Actions

Multiattack. The oozasis makes two pseudopod attacks.

Pseudopod. Melee Weapon Attack: +8 to hit, reach 15 ft., one creature. Hit: 13 (2d8 + 4) bludgeoning damage plus 10 (3d6) acid damage, and a target that’s Large or smaller is grappled (escape DC 16) and restrained until the grapple ends. The oozasis has two pseudopods, each of which can grapple one target at a time.

Engulf. The oozasis engulfs creatures grappled by it. An engulfed creature can’t breathe, is restrained, is no longer grappled, has total cover against attacks and other effects outside the oozasis, takes 21 (6d6) acid damage at the start of each of the oozasis’s turns, and is subject to the oozasis’s Waters of Unfathomable Compulsion trait. The creature takes no damage if the oozasis chooses not to inflict any. When the oozasis moves, the engulfed creature moves with it. An engulfed creature can escape by using an action and making a successful DC 16 Strength check. On a success, the creature enters a space of its choice within 5 feet of the oozasis.

Vapors of Tranquility or Turmoil (Recharges after a Short or Long Rest). The oozasis sublimates its waters into a vapor that fills a disk centered on the oozasis, 60 feet in radius, and 10 feet thick. All creatures in the area are affected by either the calm emotions spell or the confusion spell (save DC 16). The oozasis chooses which effect to use, and it must be the same for all creatures.