Valley of the Brain Collectors as a sandbox had plenty of optional encounters. However my players are very focused, it didn’t make sense to their practical hearted characters to disturb every nest in the Scar of the Spider. They stayed on mission. So they actually minimised and avoided contact with the inhabitants totally skipping the Cthulhu Mythos inhabited Fungal Cave. Here is the leader of the Mi-Go. One of the more interesting alien races from Lovecraft. The item creation special ability I couldn’t really convert to my satisfaction. 5e doesn’t make a big deal about item creation but since the Mi-Go do make strange tech-magic items I decided to leave it in with only slight modification.
I didn’t do any kind of official conversion for the staff as my players didn’t fight Lrrhech but you can get an idea of the direction I would have gone from the weapon stat block below.
Armour Class 17 (natural armour) + bramble armour 7 (1d6 + 4)
Hit Points 234 (26d8 + 130)
Speed 30ft., fly 60 ft.
STR 16 (+2) DEX 20 (+5) CON 21 (+5)
INT 25 (+7) WIS 14 (+2) CHA 15 (+2)
Saving Throws Dex +5, Wis +5
Skills Perception +8, Buff +8, Disguise +8, Heal +8, Religion +10
Damage Resistances fire, lightning; bludgeoning, piercing
Damage Immunities cold, poison
Condition Immunities blinded, deafened, frightened
Senses blindsight 10ft., darkvision 120ft., passive Perception
Languages Telepathy 60 feet. Don’t speak though there is a humming sound when they use telepathy.
Challenge 12 (8,400 XP)
Deceptive. A mi-go is a master of deception. It has advantage on Bluff and Disguise checks. Bluff and Disguise are always class skills for a mi-go.
Droning Pipes. Enemies within 30 feet of Lrrhech gain disadvantage on Wisdom saving throws while they can hear it’s prayers to The Black Goat.
Evisceration (1/Turn). A mi-go’s claws are capable of swiftly and painfully performing surgical operations upon helpless creatures or those it has grappled. When a mi-go makes a successful grapple check, in addition to any other effects caused by a successful grapple, it deals sneak attack damage to the victim. The mi-go deals an extra 13 (4d6) damage when it hits a target that is grappled or helpless with an attack.
Fleshworm Infestation (Recharge 5~6). With a touch, Lrrhech causes an infestation of ravenous worms to manifest in the target’s flesh. Treat this as a poison effect that can only be cured by dispel evil. A creature subjected to this fleshworm must succeed on a DC 17 Constitution saving throw or take 10 (3d6) poison damage, and must repeat the saving throw at the start of each of its turns. On each successive failed save, the character takes 3 (1d6) poison damage. After three successful saves, the poison ends.
Magic Resistance. Lrrhech has advantage on saving throws against spells and other magical effects.
Starflight. A mi-go can survive in the void of outer space. It flies through space at incredible speeds. Although exact travel times vary, a trip within a single solar system normally takes 3d20 months, while a trip beyond normally takes 3d20 years (or more, at the DM’s discretion)—provided the mi-go knows the way to its destination.
Summon Monstrous Aid. Lrrhech may call an earth elemental – which appears as a cross between an eel and an octopus made from the soggy fungus that fills its cavern – but is otherwise treated as a normal earth elemental.
Tech-Magic. A mi-go possesses the ability to create strange items that blur the line between magic and technology, given time and resources. This ability allows a mi-go to ignore any prerequisite skill ore feat requirements and spellcasting requirements for creating a magic item; the resulting item is always mi-go technology. A mi-go can use the Medicine skill to craft mi-go technology. When a mi-go uses this ability to craft an item, it must use a larger amount of strange ingredients and expendable resources — this effectively doubles the gp cost to create the item.
Wooden Fists. Lrrhech has fists as hard as wood covered in tiny thorns. Treat its fists as magical weapons.
Multiattack. Lrrhech makes two claw attacks and one Staff of the Dark Tapestry attack.
Claw. Melee Natural Weapon Attack: +8 to hit, reach 5 ft.; one target.
Hit: 19 (4d6 + 5) piercing damage plus target is grappled. Escape DC is 17 vs. Strength (Athletics) or Dexterity (Acrobatics).
Staff of the Dark Tapestry. Melee Weapon Attack: +9 to hit, reach 5 ft.; one target.
Hit: 19 (1d8 + 3) bludgeoning damage plus 3 (1d6) lightning damage and one of the staff’s spell affects may be delivered to the target. Spell DCs are all 17.
- Confusion: Wisdom 17 at the end, roll each turn (PHB pg. 224).
- Darkness: Will use this to escape if need be – 15ft sphere (PHB pg. 230).
- Fear: Wisdom 17 when affected and not in LOS. Will take the dash action and gain the frightened condition (PHB pg. 239).
- Irradiate: Low radiation in a 10 ft. sphere. Does not linger. Constitution 17 or suffer one level of exhaustion. A critical failure on the roll indicates a mutation affect as well.
Staff of the Dark Tapestry (see page 63 of the Valley of the Brain Collectors);
This unnaturally graceful creature has a bulbous fungoid lump for a head, spiny insectoid wings, and a tangle of spiky, clawed legs.