Innate Spellcasting. The dreamweaver's innate spellcasting ability is Charisma (spell save DC 15). It can innately cast the following spells:
At will: sleep
1/day: hypnotic pattern
Limited Telepathy. The dreamweaver can magically transmit images to any creature within 120 feet of it. This form of telepathy doesn't allow the receiving creature to telepathically respond.
Magic Resistance. The dreamweaver has advantage on saving throws against spells and other magical effects.
Peaceful Dreaming. The dreamweaver sends a wave of peaceful energy in a 30-foot cone. All creatures within the cone must make a Wisdom saving throw against a DC of 15, or else become Charmed. A creature that has been charmed by this effect is Incapacitated. Each time this creature takes damage it may repeat the saving throw, ending this effect on a success.
Restless Nightmare. The dreamweaver sends a wave of evil energy in a 30-foot cone. All creatures within the cone must make a Wisdom saving throw against a DC of 15, or else become Frightened. A creature that has been frightened by this effect is Incapacitated while the dreamweaver can see it. Whenever this creature ends its turn with total cover from the dreamweaver it may repeat the saving throw, ending this effect on a success.
Dream Siphon (Recharge 6). All creatures on the same plane of existence of the dreamweaver that are Charmed by it take 17 (2d12+4) Psychic damage. The dreamweaver regains hit points equal to the amount of damage dealt, not exceeding its maximum hit points.
Mad Hallucination (Recharge 6). All creatures that the dreamweaver can see that are Frightened by it take 17 (2d12+4) Psychic damage and must make a Charisma saving throw against a DC of 15. On a failed save the creature's Charisma score is reduced by 1d4. The creature dies if this reduces its Charisma to 0. Otherwise, the reduction lasts until the target finishes a short or long rest.
A silent, flattened form hovers over a sleeping child, its body a mass of netted strings of many colours that seem caught in an unfelt wind. The movement stops for a moment, and then the widest part of its body rises toward you, the woven eye at the centre of its form focusing on you despite the shadows.
Woven of Good Intent. The dreamweaver was originally crafted by the kalashtar, who aimed for a method to take the horrific nightmares of the Dreaming Dark and filter them into light. The earliest dreamweavers were small woven creatures that would sit upon a kalashtar as it dreamt or meditated, absorbing the bad dreams and allowing the light to fill their minds instead.
Dreaming Dark Corruption. As the dreamweavers absorbed more nightmares, they began to grow to outrageous sizes. The evil within quickly became a threat as the dreamweaver took on evil minds of their own. In a final attempt to balance the dreamweavers, the kalashtar began to feed to them good energy and peaceful dreams -- but the experiment failed, and instead the dreamweavers engorged further and developed a particular taste for the sweetness of dreams.
Gluttonous Predators. Dreamweavers are evil beings that look solely to feed on the dreams and nightmares of mortal creatures. Due to their base nature, they can occasionally be found in the control of evil fey or fiends who use the dreamweaver's power for their own benefit, offering in exchange an endless bounty of dreams. These creatures have a tendency to lurk in forests and caves near humanoid settlements, entering those settlements under the cover of night to feed.