The Great Race of Yith
At this point during the conversion of the Cthulhu Mythos in the AD&D Deities & Demigods for use with 5E D&D to point out the one major flaw with this section of the book: It doesn’t really stay true to the source material. This becomes most obvious, I think, with our next creature.
In H. P. Lovecraft’s tales, the Great Race of Yith have highly developed mental powers, and the AD&D rules hit that point by giving the Great Race some potent psionic ability. What is missing from the Great Race’s description, however, is their most impressive ability, which is their ability to project their minds across time and space to forcibly inhabit the bodies of other creatures. During the time the Yithian’s mind inhabits, say, a human, that human’s mind occupies the alien body of the Yithian. In other words, the Great Race forcibly swaps bodies with another creature, doing so across both time and space, more or less at will.
These creatures populated the world eons ago and their cities still exist buried in deserts or other out of the way places. They had a highly advanced scientific civilization, with psionics rather than magic. (Deities & Demigods, page 45)
Great Race of Yith
Large aberration, lawful neutral
Armor Class 15 (natural armor)
Hit Points 84 (8d10+40)
Speed 45 ft.
Ability Scores STR 23 (+6), DEX 7 (-2), CON 20 (+5), INT 26 (+8), WIS 19 (+4), CHA 15 (+2)
Saving Throws CON +9, WIS +8
Skills Arcana +12, History +12, Insight +8, Investigate +12, Perception +8
Senses truesight 120 ft., passive Perception 18
Languages telepathy 240 ft.
Challenge 10 (5,900 XP)
Innate Spellcasting (Psionics). The Yithian’s innate spellcasting ability is Intelligence (spell save DC 20). It can cast the following spells, requiring no material components:
At will: dimension door
3/day: modify memory, telepathic bond
1/day: foresight (self only), mind blank (self only), time stop
Actions
Multiattack. The Yithian attacks twice with its pincers.
Pincers. Melee Weapon Attack: +10 to hit, one target. Hit: 10 (1d8+6) slashing damage.
Lightning Gun. The Yithian’s lightning gun fires a stroke of lightning forming a line 300 feet long and 5 feet wide from the Yithian in a direction it chooses. Each creature in the line must make a DC 13 Dexterity saving throw. A creature takes 14 (4d6) lightning damage on a failed save, or half as much on a successful one. The lightning ignites flammable objects in the area that aren’t being worned or carried. A lightning gun has 8 charges, after which it cannot fire until its power source is replaced.
Mind Swap. The Yithian projects its psyche through time and space, across any number of years or miles, but not from one plane to another. It picks a creature at its destination. The target must make a DC 20 Wisdom saving throw. On a failed save, the target and the Yithian swap minds. The Yithian retains its INT, WIS, and CHA, and it uses the target’s STR, DEX, and CON, but it makes Dexterity checks and saving throws at disadvantage. The Yithian retains its truesight, skills, telepathy, psionics, and Mind Swap. It gains the AC, hit points, senses, languages, and the physical abilities and characteristics of the target. The target retains its own INT, WIS, and CHA, and similarly gains the STR, DEX, CON, and other physical characteristics of the Yithian. The Yithian can communicate telepathically with the target. Once per long rest, the target can make a new Wisdom saving throw. If the saving throw succeeds, the Mind Swap is reversed.
Reactions
Quick Mind. If a target resists or overcomes the Yithian’s Mind Swap, the Yithian may choose a new creature to target with Mind Swap as a reaction.
