Hi yes it is I Moth.
So as I was writhing on the main Discord group, the Mod feels with exponential possibility, but there's no "risk-reward" you can use as many Dimensional Doors, and tear through reality as much as you want with little to no consequences.
Additionally, Limbo feels...empty, I get that it's a punishment for trying to evade a pocket dungeon in unfair ways, but still, I feel like it needs something to be more than just "run to the float water thingy".

-Enter the Dimensional Shambler.

Dimensional Shambler come directly from H.P Lovecraft work.
Dimensional Shamblers are humanoid inter-dimensional hunters that tear open "cracks" between dimension to hunt prey, mainly humans, who they kidnap.

In the mod Dimensional Shamblers would be the risk-reward system where basing on how much time X Player used any Rift or DDoor in a span of a variable amount if time between each seed which is minimum a minute or so.

Were a player in a minute use the door, let's say...35 times? A chat message on the lines of "The boundaries of the universe become thinner" would be displayed, were the player continue to recklessly abuse of the DDoors, he would become a target for the rest of the playthrough.
After that not only Enderman spawnrate dramatically increases, but also from any DDoor there's the chance of a Dimensional Prowler to spawn, Prowlers are quadrupedal creatures maroon/black, with no eyes and a large bulb-shaped maw, they are fairly weak but very fast, these ones can only spawn from DDoors or open Rifts the player can traverse too, Prowlers will attack anything but undead mobs

However the real danger are the Dimensional Shambler Stalkers/Hunters/Snatchers.

These three mobs have minimal difference between eachother, mainly only their bodies Hue which is different from each one, Stalkers being predominantly black, Hunters of a dark crimson and Snatchers bluish, all of them look like skinny humanoids, 4 blocks tall hunched over and with the arms slightly bent forward on the elbow, they also will attack any not-undead passive mob.
All of these Shamblers can spawn anywhere by creating a temporary Rift, these Rifts will open somewhere nearby the player and spawn between one to two Shamblers, Prowlers can spawn from there too.
The Rift can't be traversed by the player, it will despawn when all Shamblers in the area die or despawn.

Each of these Shamblers has different ability and AI and is a force to be reckoned with as they have little less HP than Iron Golem but can move faster than the player walking, but slower than the player running.

Dimensional Shambler Stalkers are ambush based.

When they spawn they won't make any noise, only footstep, they'll prefer to attack the player or other passive mobs from behind and their ability is exactly that, dealing a whopping 2x damage from behind, additionally they will tend to hide from sunlight and have more spawning chance in the night than day.

Dimensional Shambler Hunters are purely brute force,

they will tend to spawn closer to the player, even cutting open a Temporary Rift right in their face, they will spawn aggroed to the player and immediately attack, were they too far from the player they may teleport to him by creating two rifts that last for a split-second.

Dimensional Shambler Snatchers are by far the worst, and they use indirect ways to fight the player.

Dimensional Shambler Snatchers will rush to the player as soon as they see them, their first hit on the player will instantly teleport the player and the Snatched into a DDoors pocket Dimension or straight up into a Dimension like Nether or such, this DDoors pocket Dimension can range from:

A: a forest

B: a ruins of some form

C: a weird Limbo-esque place composed by Unraveled Fabric mixed with other structures.

D: were Thaumcraft installed, the Outer Lands

E: were Abyssalcraft installed, Omothol

F: Limbo

G: Nether Fortress

And more.

When the player and Snatchers are TPed, a Stable Rift that can be traversed, will spawn when the Snatcher is killed additionally a loot chest will spawn somewhere around the area the player is TPed to.

Were the Snatched too far away from the player he'll open split seconds rift to let out Dimensional Prowlers around the area, if a Prowler spots the player, the Shambler is aggroed.

While the Shamblers are a pretty large threat, they have the possibility to drop truly valuable gear, additionally, Prowlers can be tamed to become invaluable pets, the taming process involves using meat in order to lure one in a confined area and then feeding him a "meaty treat" composed by mutton, steak, chicken, porkchop, spider eye, rotten flesh, ender pearl and a bone, you need between 1 and 5.

With the use of 3 eye of ender, a "Meaty Treat" and 3 nether warth you can craft the "Shambler Delice" feeding it to your tamed Prowler between 2 to 7 times will make him grow into a Shambler of a random type between the main three.

A tamed Shambler is invaluable and has different perks depending on their type.

Stalkers will help the player by attacking any hostile mob the player has hit.

Hunters will allow the player to do short but frequent teleportation through their rifts.

Snatchers will TP a player away from danger when he's low HP.

The drawback is that your fellow eldritch horrors have to be fed every once in a while else they'll attack passive mobs, and if left unattended for too long they might become hostile to you themselves, additionally all Enderman will be aggroed on you even if you don't disturb them, after all you are maintaining a creature which feeds off enderman.