These beasts were invented by a poster named Camu on the Wizards of the Coast forums, for a collective world-building game that we were both involved in. He had me help with the stats for his creations, and I am now - with his permission - reposting them here. Kudos to Camu for making up the most awesome epic-level aberrant threat I've encountered in DnD to date.
Worth noting is that I did change the Tsarok-Hem a little bit from their original concept. In the world-building game, they were flying creatures that inhabited a liquid sea in the world's upper atmosphere. I changed them into Far Realms creatures for this blog post, so that they can be more easily worked into traditional DnD settings, and because that concept allows for more mechanically interesting abilities.
...
It is said that beyond the world - beyond all the worlds that "exist" in the sense that we can understand - there lies a place known as the Far Realms. "Place" may not be the best term for the Far Realms; they aren't simply a location, but an existence, a state of being that encapsulates everything that 
doesn't work in the universe as we know it. The Far Realms are beyond description, beyond rationality, beyond any system of cause and effect that a mortal brain could follow. The beings that reside in these Realms are similarly alien, and almost without exception their presence is extremely hazardous to normal creatures.
The question most frequently asked about the Far Realms is "where are they?" Most scholars will envision the Far Realms as an endless, amorpheous sea in which the universe floats as a bubble of order. A smaller number would have one imagine the Far Realms as existing outside of time, ending before the beginning of the timeline and resuming after its end. The truth, however, is far more unpleasant:
 the Far Realms are all around us, at all times.
Space extends into more directions than a human can percieve. Every plane of existence in the universe is just that; a three dimensional plane within a cosmos with more than three dimensions, as flat and encompassing as a sheet of paper. The Far Realms is everything that exists outside and around the boundaries of the planes, and is infinitely more complex and geometric. Many of the inhabitants of the Far Realms exist in four or five spacial dimensions themselves, moving through our 3D worlds like a man stepping through so many curtains. Unfortunately, some of these beings have an interest in individual three-dimensional realms. Of these interested higher beings, none or more malevolent and powerful than the Tsarok-Hem.
The tsarok-hem are a race of highly intelligent, spider-like creatures whose bodies extend into one more spacial dimension than those of our plane. As a result, the tsarok-hem appear to only be partially there, their limbs and appendages blossoming out of the air in a radial fashion and moving around in a rapid, disconcerting way. By stepping "around" our dimension, they can even land different parts of their bodies in two places at once. Tsarok-hem are strictly fungivorous, and feed on a certain, alien mold or fungus that always accomponies them. This fungus can feed and grow on just about any organic matter, and the tsarok-hem have no qualms about killing sapient beings to grow their parasitic crops.
The Tsarok-Hem and their minions have conquered many 3D worlds, and seek to do the same to our own, turning the known planes into more fungus farms to feed their ever-growing population. There is a barrier that makes it difficult for them to step into our plane in person, but should they ever find a way to overcome theis obstacle, it may well be the end of the world.
Physically, a tsarok-hem appears to be a ball of chitinous, black limbs - like those of a spider or crustacean - that seem to reach out from a central point that warps light around itself. These limbs madly scuttle and chatter to bring the vortex across solid surfaces, with tentacles, feelers, and pincerlike jaws and eyestalks occasionally appearing from the center. 
Tsarok-Hem Lore (Arcana, Dungeoneering):
DC 25: The Tsarok-Hem are a force that lurk in the Far Realms, just beyond the borders of our perceived reality, awaiting the chance to invade and end all natural life. They can exist in several places at once, due to their extradimensional nature. There is an infectious, plaguelike mold or fungus that is associated with them.
DC 30: Tsarok-Hem scuttle endlessly through the planes of the Far Realms, seeking lands to conquer and beings to enslave or consume. They see three-dimensional creatures as animals beneath contempt, and - despite having a concept of morality among their own kind - find nothing wrong with abusing a human or the like. They have a hierarchical society, led by wizened "defilers" who can use their magic to spread the plague mold on which the tsarok-hem feed.
DC 35: The tsarok-hem are prevented from stepping into our plane by some unknown barrier, but they have found a way of sending minions and creations of theirs through. The 
swordwings, among other aberrations, are tsarok-hem creations, being grown from a specially engineered variation of plague-mold that forms their underdark hives.
Tsarok-Hem Demolisher; Level 28 Elite Brute (leader) (26,000 XP)
Huge aberrant magical beast
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Initiative +19 
Perception +20
HP 524 
Bloodied 262
AC 42 
Fortitude 43 
Reflex 42 
Will 40
Speed 7; climb 7 (spider climb)
Skills +27 Intimidate, +25 Insight
Resist psychic 25
Saves +2
Action Points 1
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Passive
-
aura 
Bolster Aberrations aura 3; allied aberrant creatures of  twenty-seventh level or lower gain a +1 bonus to attack rolls against  creatures they have Combat Advantage over.
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Standard Actions
-
basic melee attack 
Flailing Claws (at will):
Reach 2; +35 vs. AC; 4d12+10 damage; if the target is still within reach at the beginning of its next turn, make another 
Flailing Claws attack against it. 
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Move Actions
-
Dimensional Step (once per round, at will):
Teleport 6 squares. Until the beginning of its next turn, the tsarock-hem occupies two places; the place it teleported from, and its “current” position. The tsarock-hem‘s previous position cannot move or act, but provides flanking and can make opportunity attacks. Auras and close bursts extend out from both positions.
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Minor Actions
-
melee 
Bite (minor; once per round, at will):
Requires Combat Advantage; +35 vs. AC; 3d10+9 damage and target is grabbed. The demolisher can move and fight unimpaired while grabbing a Medium or smaller creature, and does not need to make a grapple check to move its victim. The demolisher receives a +2 bonus to attack rolls when using this ability against a creature it is already holding.
-
Summon Swordwings (encounter):
Two 
Swarmwings appear in vacant squares within 5 and act after the tsarok-hem. Do not award XP for defeating these creatures.
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Reactions
-
close burst 
Warping Claws (when first bloodied):
Close burst 3; make a 
Flailing Claws attack against all enemies within the area.
---
close burst 
Dying Eversion (when reduced to zero hp):
Close burst 3; creatures within the area are pulled one square. The tsarok-hem’s carcass vanishes.
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Alignment Evil
Languages telepathy (20 squares)
Str 26 (+22) 
Con 30 (+24) 
Dex 20 (+19) 
Int 26 (+22) 
Wis 22 (+20) 
Cha 26 (+22) 
Demolishers know that their physical strength and interdimensional nature allow them to overpower almost any three-dimensional creature in combat, and are thus nearly fearless. These are the footsoldiers of the tsarok-hem, tasked with the genocide of any lesser race that stands in the way of tsarok-hem goals. Demolishers might also occupy positions of middle management, relaying the orders of the Defilers to lesser minions and organizing small-scale operations on their own.
Tactics
A demolisher tries to stay close to its enemies at all times, using 
Dimensional Step to pursue and flank the enemy, cutting it off if it tries to escape. If the demolisher has aberrant allies present, it will use 
Dimensional Step to help them flank as many enemies as possible, so that they can benefit from its 
Bolster Aberrations aura.
The demolisher will use 
Bite every turn, trying to keep an enemy in its jaws at all times. If it grabs a fragile character (like a controller), it may transfer it to its other 
Dimensional Step location to seperate it from its allies and make it an easier target for the tsarok-hem's own allies.
If the demolisher believes it is going to lose, it will attempt to flee, saving its 
Summon Swordwings ability for the end of the battle to cover its retreat.
Tsarok-Hem Terrorizer; Level 29 Elite Artillery (leader) (30,000 XP)
Huge aberrant magical beast
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Initiative +23 
Perception +21
HP 292 
Bloodied 146
AC 41 
Fortitude 43 
Reflex 43 
Will 43
Speed 7; climb 7 (spider climb)
Skills +28 Intimidate, +28 Stealth
Resist psychic 25
Saves +2
Action Points 1
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Passive
-
aura 
Bolster Aberrations  aura 3; allied aberrant creatures of twenty-seventh level or lower gain  a +2 bonus to attack rolls against creatures that have attacked the  Terrorizer since the end of the Terrorizer’s last turn.
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Standard Actions
- 
basic melee attack 
Forceful Claw (at will):
Reach 2; +36 vs. AC; 3d10+10 damage and target is pushed 1 square.
-
basic ranged attack 
Psychic Creeper (at will):
Range 10; +34 vs. Will; 4d10+10 psychic damage and ongoing 20 (save ends); if this attack hits, make a secondary attack against another target within 5 squares of the primary target; +34 vs. Will; 4d8+10 psychic damage. If the target is 
dazed, it is also 
immobilized until the end of its next turn (save ends).
-
blast 
Narcotic Spore Cloud (recharge 5, 6):
Blast 6; +34 vs. Fortitude; 3d10+10 poison damage and target is 
dazed and becomes vulnerable 15 to psychic damage (save ends both).
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Move Actions
-
Dimensional Step (once per round, at will):
Teleport 6 squares. Until the beginning of its next turn, the tsarock-hem occupies two places; the place it teleported from, and its “current” position. The tsarock-hem‘s previous position cannot move or act, but provides flanking and can make opportunity attacks. Auras and close bursts extend out from both positions.
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Minor Actions
-
Summon Swordwings (encounter):
Two 
Swarmwings appear in vacant squares within 5 and act after the tsarok-hem. Do not award XP for defeating these creatures.
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Reactions
-
close burst 
Dying Eversion (when reduced to zero hp):
Close burst 3; creatures within the area are pulled one square. The tsarok-hem’s carcass vanishes.
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Alignment Evil
Languages telepathy (20 squares)
Str 24 (+21) 
Con 26 (+22) 
Dex 28 (+23) 
Int 26 (+22) 
Wis 24 (+21) 
Cha 28 (+23)
Just as demolishers destroy the bodies of the tsarok-hems' enemies, terrorizers can crush their minds. The tsarok-hem are a race of great willpower and psychic fortitude, and their four-dimensional minds can engulf and crush the mind of a lesser being if they receive the correct training. Terrorizers support the tsarok-hems' melee units in combat, and - like demolishers - can serve as middle management over other aberrant creatures and slaves.
In addition to their natural and psionic armaments, terrorizers are equipped with a fungal symbiont that can spray a cloud of narcotic spores at the enemy, making them more vulnerable to the creature's psychic attacks.
Tactics
Unless the enemy is outnumbered or badly wounded, terrorizers stay back from the front line, letting more melee-oriented tsarok-hemk or minions engage in melee. They use their 
Psychic Creepers strategically, seeking to immobilize the enemies that are causing the most trouble for the terrorizer's allies (often choosing to immobilize Defenders and Strikers so that the terrorizer's friends can move around them). If they have a good opportunity to spray their 
Narcotic Spore Cloud over several enemies, they will do so as early as possible, and then concentrate their 
Psychic Creepers on those who are effected (the terrorizer can tell if someone is being effected by the fog or not).
If approached in melee, the terrorizer will use its 
Forceful Claws to knock the offender back, and call for an ally to take care of it before it can return. If an enemy proves persistent, the terrorizer will use 
Dimensional Step to move away from it and (hopefully) behind a friend. Like Demolishers, they will wait until late in the battle to summon their swordwings.
Tsarok-Hem Defiler; Level 30 Elite Controller (leader) (38,000 XP)
Huge aberrant magical beast
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Resist psychic 25
Initiative +21 
Perception +23
HP 428 
Bloodied 214
AC 46 
Fortitude 42 
Reflex 44 
Will 45
Speed 7; climb 7 (spider climb)
Skills +29 Arcana, +30 Intimidate, +28 Heal
Saves +2
Action Points 1
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Passive
-
aura 
Bolster Aberrations  aura 3; allied aberrant creatures of twenty-seventh level or lower gain a  +1 bonus to attack rolls against creatures infected with 
Plague Mold.
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Standard Actions
-
basic melee attack
 Infectious Claw (standard):
Reach 2; +34 vs. Fortitude; 4d12+10 damage and target contracts 
Plague Mold.
---
ranged 
Visions of Doom (encounter):
Range 10: +34 vs. Will; 5d12+9 psychic damage and target is 
stunned (on the first successful save, the target is 
dazed rather than 
stunned; on the second save, the 
daze ends).
Miss: 2d10+9 psychic damage and target is 
dazed (save ends).
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Move Actions
-
Dimensional Step (once per round, at will):
Teleport 6 squares. Until the beginning of its next turn, the tsarock-hem occupies two places; the place it teleported from, and its “current” position. The tsarock-hem‘s previous position cannot move or act, but provides flanking and can make opportunity attacks. Auras and close bursts extend out from both positions.
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Minor Actions
-
Summon Swordwings (encounter; recharges when first bloodied):
Four 
Swarmwings appear in vacant squares within 5 and act after the tsarok-hem. Do not award XP for defeating these creatures.
-
ranged 
Tumorous Growth (at will):
Target must be infected with 
Plague Mold; range 5; +36 vs. Fortitude; 4d8+10 disease damage and target is 
restrained (save ends). The target cannot be attacked with 
Tumorous Growth again until it has saved against the restraint. The Defiler does not provoke opportunity attacks by using this ability.
---
burst 
Plague Spores (at will):
Target must be restrained by
 Tumorous Growth; burst 5 centered on an infected target within 10; targets enemies, but not the enemy on which the burst is centered; +34 vs. Fortitude; 2d8+10 disease damage and contract
 Plague Mold. The Defiler does not provoke opportunity attacks by using this ability.
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Reactions
-
close burst 
Dying Eversion (immediate reaction; when reduced to zero hp):
Close burst 3; creatures within the area are pulled one square. The tsarok-hem’s carcass vanishes.
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Alignment Evil
Languages telepathy (20 squares)
Str 24 (+22) 
Con 28 (+24) 
Dex 22 (+21) 
Int 28 (+24) 
Wis 26 (+23) 
Cha 30 (+25)
The greatest of the tsarok-hem are the defilers, who have the ability to spread the Plague Mold on which their civilization depends. It is not known if the defilers are a seperate biological caste, special from birth, or simply older and wiser tsarok-hem that have been taught these skills. The defilers are the masterminds behind the attempted invasion of the mortal world, and it is they who created the special-bred fungi used by the lesser tsarok-hem castes (such as the spore-sprayers used by the Terrorizers, or the interdimensional device that is used to summon swordwings onto the battlefield). They are also the architects of several bio-engineered servitor races, such as the swordwings.
The defilers make up a governing body among the tsarok-hem. As a result, they are likely to be well-guarded and accompanied by attendants - both tsarok and lesser creatures - wherever they go.
Tactics
The
 tactics of the Defiler are dependant on spreading 
Plague Mold. They will usually start the battle by 
Summoning Swordwings to harass the enemy and draw its fire while the Defiler 
Dimensional Steps up and lays about with 
Infectious Claws. Once several enemies have been infected, the Defiler will teleport back a few squares and use 
Tumorous Growth on anyone who's been infected, hoping to follow up with 
Plague Spores to spread the infection further without having to come back into melee. Most often, the Defiler will stay two or three squares behind the front line; just close enough for their allies to benefit from their 
Bolster Aberrations aura, using 
Dimensional Step to cover as many allies with the aura as possible.
Like the lesser tsarok-hem, a Defiler will save its second use of 
Summon Swordwings for the end of the battle, either to suddenly overwhelm the weakened enemy, or to cover the Defiler's retreat.
Plague Mold (level 27 disease)
- 
Make skill checks every hour:
Stabilize: Endurance DC 35.
Improve: Endurance DC 40.
-
Stage One: Target recieves a -1 penalty to attack rolls and speed, and gains 
vulnerable 10
 to psychic damage. 
Stage Two: Target gains only half the benefit from healing effects (including the expenditure of healing surges) and is 
weakened, in addition to the stage one effects.
Stage Three: Target is 
dazed, 
slowed,
 and takes ongoing 10 disease damage, in addition to stage one and two effects. If the target dies while suffering from Stage Three plague mold, make an attack; burst 5 centered on the victim, targets non-aberrations; +32 vs. Fortitude; target contracts 
Plague Mold. All that is left of the original victim is a human-sized lump of sticky, gray-orange fungus, which the tsarok-hem find delicious.
  
Encounters
Tsarok-Hem are meant to be the ultimate villains of an aberrant-themed campaign; defeating the Defilers in their extra-dimensional inner sanctum is a climactic battle to determine the fate of the world. A Dungeon Master would be perfectly reasonable to have every major enemy the PC's fight from levels one through thirty be working - knowingly or otherwise - for the tsarok-hem.
Obviously, the 
swordwings statted in the previous entry make good minions for a tsarok-hem battle. While the tsarok-hem can summon Swarmwings on their own, you may wish to add Swordwings, Crownwings, Blastwings, Ramwings, and Bloodwings to diversify the opposition. As the tsarok-hem themselves cover the Brute, Artillery, and Controller roles, its best to pair them with Skirmishers or Soldiers, perhaps with the occasional lurker thrown in for interest. Any epic-level aberration could theoretically be a tsarok-hem bodyguard slave, so feel free to give them whatever backup you want.