Duality. the Dreamstrider has two forms, Dreamlike and Nightmarish.

while Dreamlike, the Dreamstrider appears as a person from the memories of whoever can see it, or a mishmash of individuals if there are multiple observers. the Dreamstrider has advantage on persuasion checks while Dreamlike

while Nightmarish, the Dreamstrider appears as a monster from whoever can see it's greatest fears, or a mishmash of monsters if there are multiple observers. the Dreamstrider has advantage on intimidation checks while Nightmarish

Multiattack. The Dreamstider makes one slam attack and uses shift.

Slam. Melee Attack Roll: +10, reach 5 ft. Hit: 33 (4d12 + 7) Psychic damage.

Shift. the Dreamstrider shifts its form to either Dreamlike or Nightmarish.

Mindshape (2/day). the Dreamstrider shapes the environment in a 300ft radius into whatever it wants, creating landforms, (non-creature) plants, natural hazards, and even weather. this conversion lasts for 1 hour, after Wich the environment slowly transitions back to normal.