The Crimson (5e Environment)
From D&D Wiki
The Crimson is a single emergent living being connected to each world, sharing a hive mind, and solely I used on restoring the balance at all costs. At this time, it is feeding on the natural ebb and flow, and subsequent pull of the aetherial planes and neighboring planes, setting off chain reactions that effectively cloud both jusgement and innate alignment of those whom draw from both leylines or the astral and arcane. Subsequently throwing the balance of further by over-burdening the ever vwst and immeasurably potent quantity of mana in the multiverses, though by denizens utilizing them in the Material Planes, causing disruptions in the latent, unknowable energy of their homeworlds. Unfortunately, this still has yet to stop the metamagic flow, or the continued absorption into the hive mind, and its bodies ever growing influence over the many realms.
Thousands of worlds before the one on which you stand now have been absorbed by this being. Many misguided people have made the horrific mistake of raising the Crimson to the level of deity- conducting human sacrifices to it to placate the monstrosity or seek its favor. The Crimson gladly consumed these bodies, becoming one with them and producing terrifying beings, all who lose the ability to feel and blindly follow the hive mind. The land here is where the grass is redder and the water runs blood red. Large caves run into caverns made of fleshy stone and aberrant things.
The type of things found here are Brain of Cthulhu, Crimea, Face Monsters, Ichor Stickler, Blood Feeders, and Servant of Cthulhu, chaotic neutral Cultists, some Tieflings, Occultist and Warlock Classes, Museblade Classes, Mystiques, Summoners, Soothspeakers, Chloromancers, Necromancers.
[DM's Note: Give life to magic, not magic to life.."]