1d6 Random Encounters With The Dread Mi Go Table For Your Old School Campaigns

The Mi Go are one of Lovcraft's most recognizable alien races and yet can be encountered just about anywhere including the wastelands. They are horrific and very dangerous often seeking rare or weird mineral specimens in the deepest parts of the wastes. These horrors often have their own secret and esoteric alien agenda when adventurers encounter them. They may try to subdue the party to implant their brains in the alien metal cylinders that they use.

“For the things in the chair, perfect to the last, subtle detail of microscopic resemblance - or identity - were the face and hands of Henry Wentworth Akeley.”
― H.P. Lovecraft, The Whisperer in Darkness: Collected Stories Volume 1
Mi Go war parties encountered in the field are often on a mission and will engage with adventurers  rarely. They have a twenty percent chance of perusing some wizard or other magic user, the psychic and occult energies of individuals attracts them. The Mi Go often murder folks for their brains and place them in the metal brain cylinders that they are so fond of.

1d6 Random Encounters With Mi Go Table

1. A clutch of 1d8 Mi Go has found a rich vein of some sort of weird radioactive mineral created from  the remains of various humans caught within an atomic explosive device. They will be using it to power their forbidden alien devices and their quite aggressive. 
2. There is aura of telepathic calm that acts as a charm spell, there is a 1d8 Mi Go surgical warrior team ready to take out anyone that they meet. They're building a new faster then light bio mechanical psionic space craft and they need brains and fast. The Mi Go are choosing brain material by volume for their alien project. 
3. A Mi Go fifth level dark priest is looking for sacrifice victims and clone material. There is a an assault team of 1d4 2nd level warriors armed with laser stunning crystals that does 2d6 +1 points of damage temporary damage in a twenty foot radius. There are brain cylinders and clone banks standing by. 
4. A swarm of 1d10 Mi Go are holding dark rites to summon a Lovecraftian demon to the local space time continuum for an alien agenda. They have set up a hyperspace gate filled with "mathematically-perfect music" near a group of standing stones. Anyone who wanders within a radius of ten to twenty feet must save vs device or be hurled 1d10 light years to another alien solar system. 
5. A group of 1d8 3rd level fighters and agents belonging to the Brotherhood of the Yellow Sign are in the area with 1d4 2nd level dark priests to bring down to the area a very nasty aspect of Hastur to the local area. They have set up two very large psychic bio crystals to pull in all of the negative pseudo emotions of the area to 'gate' this horror into the area but its not too late! 
6. 1d8 2nd level  Grey warriors are in the area looking to trade psychic crystals with the stolen minds of some of the locals with their Mi Go  dark priest masters who are here to harvest the flesh they need for an alien bio construct. The reasons for the thing are unknown.

If the Mi Go are encountered on temperate or Earth like worlds there is a 20% chance of parties encountering their Grey servants who will often be armed with alien energy weapons of their own construction. Grey often construct gateways to Yuggoth for their dark masters for easier access to the local environs. Mi Go encountered in wilderness settings are often more aggressive and dangerous then those operating within

Yuggoth... is a strange dark orb at the very rim of our solar system... There are mighty cities on Yuggoth—great tiers of terraced towers built of black stone... The sun shines there no brighter than a star, but the beings need no light. They have other subtler senses, and put no windows in their great houses and temples... The black rivers of pitch that flow under those mysterious cyclopean bridges—things built by some elder race extinct and forgotten before the beings came to Yuggoth from the ultimate voids—ought to be enough to make any man a Dante or Poe if he can keep sane long enough to tell what he has seen...
—H. P. Lovecraft, "The Whisperer in Darkness"