It is the plane of ultimate law.

It is where premeditated plans are born.

It is the gear works for the multiverse.

Mechanus is where perfectly regimented order reigns
supreme. It consists of equal measures of light and dark,
and equal proportions of heat and cold. It is as predictable
as the drip of a water clock and as obvious as a tree in a
field. On Mechanus all law is reflected in a single infinite
realm of clockwork gears, all interlocked, all turning
according to their own measure. The cogs seem to be
engaged in a calculation so vast that no deity knows its
purpose, except that it is somehow a function of law.
At first glance Mechanus seems as straightforward as
anything on the Outer Planes. However, subtleties lurk
just below the surface. Every kind of law can be found in
the Clockwork Nirvana of Mechanus, from simple
maxims to devilishly twisted rules of decorum. But for the
most part, Mechanus contains no passion, illusion, or pain.
When all consciousness is completely subsumed into the
whole, perfection follows.


Mechanus has the following traits.

  • Objective Directional Gravity: The strength of gravity
    is the same as on the Material Plane but the direction is
    oriented to the face of each rotating cog. Walking
    between cogs can be dizzying for newcomers—and
    dangerous if a traveler falls between the cogs.
  • Normal Time.
  • Infinite Size: Each cog is finite, though even the
    smaller ones are as big as a typical island. The void the
    gears hang in is infinite.
  • Divinely Morphic: Lesser deities can alter Mechanus
    with a thought; ordinary creatures require spells and
    physical effort to do so.
  • No Elemental or Energy Traits.
  • Strongly Law-Aligned: Nonlawful characters on Mechanus
    suffer a –2 penalty on all Charisma-, Wisdom-,
    and Intelligence-based checks.
  • Normal Magic.


Free-standing portals from elsewhere usually connect at
the center of any given cog. Some portals lead to other
Outer Planes, Inner Planes, or even the Astral Plane or
Ethereal Plane. Some portals even lead to other cog faces.
Portals on Mechanus appear as light green coglike circles,
slowly turning. A green portal appears regularly once
per revolution of the cog it resides upon, though some
portals appear according to the interaction of several cogs
(and which ones are not always readily apparent). Once it
appears, a given portal usually remains open for at least 1
hour and possibly as long as 24 hours.


The inhabitants of Mechanus make their homes on the
cogs that turn in the void. The gear faces are normally
devoid of vegetation and native wildlife, although
colonists from other planes, including the Material Plane,
the Nine Hells, and Celestia, transform many faces into
elaborate hedge mazes, parks, or nature reserves.
The most prevalent creatures on Mechanus are not truly
living creatures at all—they’re constructs. As a group they
are called inevitables, and they exist to enforce the natural
laws of the universe. The three widely recognized types of
inevitables are kolyaruts (fugitive-hunters), maruts (foes of
those who cheat death), and zelekhuts (enforcers of
contracts). Each type of inevitable relentlessly finds and
punishes those who have committed such transgressions.
Expansionist formians have hives throughout Mechanus.
These antlike centaurs seek to colonize all they see
and incorporate all living things into their hives as
workers, serving the law of their queens.
Other clockwork creatures, apart from inevitables, also
call Mechanus home, though they have as little as possible
to do with other races.

Mechanus Petitioners

The petitioners of Mechanus often adopt a stylized version
of their mortal bodies. Despite the outward differences, all
petitioners on Mechanus are alike in their frightening
honesty and submersion of individuality. They are notoriously
literal, and some take no instruction at all for fear
of misinterpreting the speaker.
Mechanus petitioners have the following special petitioner

Additional Immunities: Fire, cold.

Resistances: None.

Other Special Qualities: None.


Movement in the Clockwork Nirvana of Mechanus is
much like movement on the Material Plane. Walking
between turning cogs seems daunting to the uninitiated,
requiring a Balance check (DC 10). This is a relatively easy
check, but failure by 5 or more means a fall between the
cogs, which deals 20d6 points of damage each round. It
takes a climb check (DC 20) to emerge from the teeth of
the cogs. Travelers can move between the cogs by flying or
teleporting through the void, of course.


Mechanus is a single infinite plane
without defined layers. The void is filled
with gargantuan interlocking wheels, like the
internal cogs of an ornately carved clock. Some connect at
right angles, and others connect along a single plane. The
wheels, also called cogs, are composed of stone, earth, and
metal ores, as if a deity carved them from the mantle of the
Material Plane.
Many of the cogs are more than a thousand miles across,
and they turn so slowly that their rotation is imperceptible.
Yet turn they do, as witnessed by much smaller
island-sized cogs that interlock with the much larger
These smaller cogs seem to turn at an almost dizzying
pace, although inhabitants feel no centripetal force once
on the surface of a small cog. The objective directional
gravity means that inhabitants won’t be spun off the edge
of a cog unless they’re standing within 10 feet of the rim.
Vision is normal on Mechanus. The plane is lit by a
white, all-encompassing light springing from the very void
for 12 hours, and is dark for 12 hours. Hearing is also
normal, though the bass rumbling of cog turning on cog is
sometimes audible near the edge of a face. Formian Hive Cogs
The formians build fabulous hive-cities on both faces of a
cog they colonize. Each colonized hive-cog holds thousands
of workers, warriors, and taskmasters, as well as
several dozen or more myrmarchs. However, each cog has
only one queen, whose commands are absolute law on the
hive cog.
Other queens rule other cogs. Usually two queens
cooperate with each other, unless each wishes to colonize
the same cog, in which case the law of the formians
demands warfare. If a queen chooses to colonize a cog by
sending a contingent guarding a precious queen larva, she
is not swayed if other creatures already reside there. After
all, what are warriors for, if not to make a cog ready for
formian colonization?
Luckily, the birth
of a fledgling
queen from the many
eggs laid happens only once every one
hundred to one thousand years. Otherwise the formians
would hold much more of Mechanus than they already do.
The Center: Travelers who move through the void of
Mechanus in the direction from which the formians
originate find that the formian-colonized cogs become
more and more frequent until noncolonized cogs are
nonexistent—millions of cogs, or perhaps more, all
crawling with formians.
At the heart of the formian realm, surrounded in all
directions by colonized cogs, lies the centermost cog
where the Scion Queen Mother resides. Formian myrmarchs
believe that the Scion Queen Mother’s cog, which
has a diameter of at least three thousand miles, is the
center cog for all Mechanus and imparts movement to all
the other cogs of the plane.
Whether true or simply a belief, the grandeur of the
two-sided hive-city that covers the surface area of the cog
is godly in its splendor. The Scion Queen Mother herself
claims the power of an intermediate deity, though this
claim is difficult to scrutinize. Thirty-three gargantuan
formian queens of maximum advancement attend the Scion Queen Mother at all times,
and even her escorts are
still dwarfed by the Scion Queen Mother’s bulk.


Inevitables are designed, constructed, and assigned tasks
to uphold various laws. It is unknown who created the
first inevitable; even inevitables claim ignorance as to their
own origin. But once created, the constructs soon learned
the trick of replicating themselves.
Neumannus is one such “factory” inhabiting a small cog.
It is a place devoid of regular life, though it is crawling
with inevitables at all times. Tall smokestacks cover both
sides of the cog and constantly belch sooty clouds from
the fires raging in forges and furnaces.
Inside, chamber after chamber is given over to crystal
molds of dizzying variety. Liquid metal is cooled, shaped,
and tempered in these molds by special constructs.
Finished pieces are assembled and animated in arcane
baths of oillike consistency. After a brief shakedown
period, the newly constructed inevitable is sent out onto
the Great Wheel with its first task.
Tasks are magically encoded on the construct in
glowing runes handed down by the Hub of Elders (each
factory has its own hub). The elders are several hundred
special inevitables that spend their time peering through
the cosmos looking for broken laws for which amends
must be paid. Sometimes, inevitables bow to other noted
authorities of law in the Outer Planes, doing their bidding
for a short period.


Clockwork creatures reside on Mechanus in a realm called Regulus and seem well
suited to it. These alien beings, called modrons,
look and act like constructs but breathe and eat like the outsiders they are.
The modrons control sixty-four cogs, and this number never varies. In truth,
modrons outwardly hold many traits in common with inevitables, but modrons are
not concerned with maintaining their own ordered society, not punishing other
creatures for broken laws. The formians have yet to test the modrons’ strength,
although such a conflict is likely as the formians continue to expand.

Other Sites on Mechanus

If the void of Mechanus is infinite, then the cogs must also
be numberless. The disks that make up the plane all
interlock, so there is no part of Mechanus that is not
connected to some other part. Technically, there is no
place a traveler can’t go if he is determined and long-lived
enough. For all its lawful conformity, Mechanus holds
countless sites of interest.

Delon-Estin Oti: This perfectly symmetrical
town is located on a far larger cog, taking up only a small part of it. Delon-Estin
Oti has twenty bordering walls, with one gate on each side. Farmers till plots
of fruits and vegetables and nurture animals just inside the gates. Seen from
above, the town looks like a spiderweb, with concentric roads radiating from
the hub, a great open space covered with grass, and a single ring of trees at
the very center. The town is one of peace and tranquility, a place where everything
is so ordered and habitual that citizens anticipate the course of time and flow
of conversation, interrupting visitors who don’t know what the future holds.
Those who seek perfect equality and freedom from the lower (and higher) passions
make their homes here. The population is a mixed collection of every race on
the Great Wheel, but all are equal and there is no ruler. Many petitioners also
reside within and around Delon-Estin Oti, happy to work the agricultural plots.
The town has a reputation as a place where seers are born and where fortune-tellers
gravitate, so visitors hoping to discover their fate are common.

Fortress of Disciplined Enlightenment: This
structure sits on its own cog, and its spires and towers rise high into the
void of Mechanus. The fortress is two miles in diameter, and some of its spires
reach twice that height. Inevitables enforcing the “don’t trespass” law patrol
the parapets, keeping a vigilant eye out for fiendish infiltrators or colonizing
formians. A group of mortals from the Material Plane called the Fraternity of
Order are the masters of the fortress. The members of the Fraternity of Order
believe that if they can but tease forth every law of the cosmos, they will
have the power of the deities. To that end, they built this stronghold on the
plane of ultimate law. A horde of clerks, functionaries, legal aides, translators,
mathematicians, philosophers, and bureaucrats staff the Fortress of Disciplined
Enlightenment. Most belong to the Fraternity of Order, though sometimes visitors
are granted access to study at the vaunted libraries of the Fortress. The libraries
extend through hundreds of rooms and hold tomes of legal volumes from all over
the Great Wheel.


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