Today’s ENterplanetary DimENsions is a spot many adventurers eagerly hunt down however few ever escape: the limitless dungeon dimension of Ostending Ostium!

There is a legend of a vault containing wealth of such abundance that even the gods envy it, a trove of treasure crammed with splendors past imagining envied throughout the multiverse. To defend this unimaginable hoard its proprietor—unknown to all and now lengthy gone—created a singular labyrinthine dungeon that grew bigger with each thoughts that entered it. The first servant to strive turned misplaced, after which the subsequent, and with every that strayed inside by no means to return the maze turned ever bigger and extra complicated. Eventually its creator too turned misplaced inside, dying like so many others. This is how the dimension of Ostium started and the way it continues to at the present time, passages morphing into and round others into a fancy of tunnels that span the entire realm.

Practically all of this aircraft’s inhabitants are useless or practically feral. Anyone present in Ostium is wandering its limitless tunnels both scrounging and scavenging to outlive, taking with pressure what they will and in search of escape, prowling for a recent meal, exploring even after dying, or engaged in a large sport of intrigue for a prize of inestimable wealth. No matter from the place they got here or why they’re there, few who discover their methods to this dimension stay lengthy sufficient to flee—although those that do convey with them treasure sufficient to attract in future victims.

Planar Traits. Ostium has the next planar traits and the Narrator ought to make use of the acid, brown mildew, darkness, dense smoke, hearth, frigid water, inexperienced slime, lava, magnetized ore, reminiscence crystals, webs, and yellow mildew encounter components. When it’s doable to take action, noticing one among these encounter components earlier than it’s too near keep away from requires a DC 16 Engineering verify.

Cadaverous Court​

The masters of Ostium are the Court of Spades, its royalty (the jack, queen, and king) lording over numerous knights of the spade unfold over a realm that extends to the aircraft’s furthest reaches. Though they now not stay these undead nonetheless have objective, toiling away to reconstruct the limitless dungeon to match the imaginative and prescient of their immortal rulers. Whatever magic the Court of Spades holds nonetheless, it’s not involiate for they’re an extension of the dimension, their legacy and the way lengthy they’ve endured right here all that retains them of their positions of energy.

When a spade is destroyed these extra lately reworked improve in information and energy, their understanding of Ostium changing into all of the larger—a number of occasions a jack has been killed and the knight of the spade beneath elevated, and myths unfold amongst this place’s inhabitants declare the king is the final corporeal survivor from the world that when was. Spades ruthlessly vie to rise within the hierarchy, manipulating visiting adventurers into killing rivals in trade for secreted treasures (and people with essentially the most to realize typically have essentially the most to supply).

Superb Spade. The final little bit of a slain knight of the spade’s essence turns into trapped in its shovel: a knight’s spade.

Knight’s Spade​

Weapon, uncommon (requires attunement; value 850 gp)
Crafting Components: Soul of an undead from Ostium
This shovel is a martial melee weapon that offers 1d6 magical slashing harm plus 1d4 necrotic harm.

While you’re attuned to and wielding the shovel, you’ll be able to use the Transform Area characteristic.

Transform Area. You can use a bonus motion to reshape a 5-foot dice adjoining to your self, altering the realm’s elevation or creating and eliminating holes, partitions, and pillars. Changes that end in unstable terrain are topic to break down. Any Large-sized or smaller creature within the space makes a Dexterity saving throw with benefit (towards your fight maneuver or spell save DC) or it falls susceptible in a sq. chosen by you that’s adjoining to the realm. If the chosen sq. is occupied by a creature of Medium dimension or smaller, it makes a Dexterity saving throw or additionally falls susceptible.

Once you may have used this characteristic a lot of occasions equal to half your proficiency bonus, you can not achieve this once more till you end a protracted relaxation. While on the aircraft of Ostium, you need to use this characteristic a lot of occasions equal to your proficiency bonus, regaining expended makes use of if you end a brief or lengthy relaxation.

Knight of the Spade Challenge 5​

Medium undead 1,800 XP
AC 15 (pure armor)
HP 82 (11d8+33; bloodied 41)
Speed 30 ft. (50 ft. mounted)

Proficiency +3; Maneuver DC 14
Saving Throws Str +7, Int +4
Skills Deception +3 (+1d4), Engineering +4, Insight +5, Perception +5 (+1d6)
Damage Resistances chilly, necrotic, psychic; harm from nonmagical weapons
Damage Immunities poison
Condition Immunities charmed, fatigue, frightened, paralyzed, poisoned, shocked, strife
Senses darkvision 120 ft., passive Perception 18
Languages Common

Glamered. Until it takes harm or is infuriated by a profitable Intimidation verify opposed by its Insight verify, the knight and its mount look like a standard humanoid knight and warhorse.

Magic Resistance. The knight has benefit on saving throws towards spells and different magical results.

Mounted. The knight rides a skeletal warhorse.

Undead Nature. The knight doesn’t require air, sustenance, or sleep.

ACTIONS
Multiattack. The knight assaults thrice.

Spade. Melee Weapon Attack: +6 to hit, attain 5 ft., one goal. Hit: 6 (1d6+3) slashing harm plus 3 (1d6) necrotic harm.

Spade Slash. Ranged Spell Attack: +5 to hit, vary 30/90 ft., one goal. Hit: 9 (2d6+2) necrotic harm.

BONUS ACTIONS
Spade Magic (Recharge 4–6). The knight reshapes a 5-foot dice adjoining to it, altering the realm’s elevation or creating and eliminating holes, partitions, and pillars. Changes that end in unstable terrain are topic to break down. Any Large-sized or smaller creature within the space makes a DC 14 Dexterity saving throw or falls susceptible in a sq. chosen by the knight that’s adjoining to the realm. If the chosen sq. is occupied by a creature of Medium dimension or smaller, it makes a DC 14 Dexterity saving throw or additionally falls susceptible.

Unforgiving Hilt. When the knight hits a creature twice on the identical flip with its spade, it makes use of the Shove primary maneuver towards the creature.

REACTIONS
Dig In. The knight assaults a susceptible creature with its spade.

Noble of the Spade Challenge 15​

Legendary Medium undead 13,000 XP
AC 17 (pure armor)
HP 247 (26d8+130; bloodied 123)
Speed 40 ft.

Proficiency +5; Maneuver DC 17
Saving Throws Str +9, Int +8
Skills Deception +7 (+1d6), Engineering +8 (+1d4), History +8, Insight +9 (+1d6), Perception +9 (+1d8)
Damage Resistances chilly, pressure, necrotic, psychic; harm from nonmagical weapons
Damage Immunities poison
Condition Immunities charmed, fatigue, frightened, paralyzed, poisoned, shocked, strife
Senses darkvision 120 ft., passive Perception 23
Languages Common

Glamered. Until it takes harm or it’s infuriated by a profitable Intimidation verify opposed by its Insight, the noble seems to be a standard humanoid.

Innate Spellcasting. The noble’s spellcasting potential is Wisdom (spell save DC 17, +9 to hit with spell assaults). It can innately forged the next spells, requiring no materials elements:

At will: command, detect magic, minor phantasm, misty step, transfer earth​

3/day every: create meals and water, detect ideas, magic missile, main picture, mirror picture, non secular weapon​

1/day every: arcane sword, wall of pressure​

Legendary Resistance (3/Day). When the noble fails a saving throw, it may possibly select to succeed as a substitute.

Magic Resistance. The noble has benefit on saving throws towards spells and different magical results.

Ostium Master. When the noble casts command it is ready to goal undead with the spell, and when it casts transfer earth it may possibly have an effect on any constructing materials corresponding to steel, stone, and wooden.

Royal Annoyance. After a creature has succeeded on a saving throw towards a command from the noble, it has benefit on saving throws towards the noble’s command spells.

Undead Nature. The noble doesn’t require air, sustenance, or sleep.

ACTIONS
Multiattack. The noble assaults 4 occasions.

Royal Halberd (Jack Only). Melee Weapon Attack: +9 to hit, attain 10 ft., one goal. Hit: 9 (1d10+4) magical piercing or slashing harm plus 4 (1d8) pressure harm.

Royal Wave (Queen Only). Melee Spell Attack: +9 to hit, attain 5 ft., one goal. Hit: 15 (2d10+4) pressure harm.

Royal Scepter (King Only). Melee Weapon Attack: +9 to hit, attain 5 ft., one goal. Hit: 7 (1d6+4) magical bludgeoning harm plus 9 (2d8) pressure harm.

REACTIONS
Royal Reprisal (Recharge 5–6). When the noble is broken by a creature it may possibly goal the creature with a command spell.

LEGENDARY ACTIONS
The noble can take 3 legendary actions, selecting from the choices under. Only one legendary motion can be utilized at a time and solely on the finish of one other creature’s flip. It regains spent legendary actions at the beginning of its flip.

Attack. The noble makes a melee assault.

Royal Illusion. The noble casts mirror picture.

Royal Mind (King Only). The noble casts detect ideas or main picture.

Royal Weapon. The noble assaults with a magical weapon it has already conjured (both an arcane sword or non secular weapon).

Spell (Queen Only). The noble casts a spell.

Step Lightly (Jack Only). The noble strikes its Speed with out upsetting alternative assaults.

Royal Body (King Only; Costs 2 Actions). The noble regains 16 (2d10+5) hit factors.

Royal Command (Costs 2 Actions). The noble casts command and its goal has drawback on the saving throw.

Disturbing Dimensions​

Ostium has grown itself in the identical form and type because the stone construction it initially was, however with centuries and millennia of fixed reconstruction its structure has warped and devolved to pressure the thoughts.

Confusing Construction. A creature can perceive the structure of Ostium with an Engineering verify (DC 10 + 1d8), gaining benefit on checks to observe tracks or decide its location to a different level within the dimension. On a results of 20 or greater the creature suffers a long-term psychological stress impact, or on a failure it suffers a stage of strife. Oddly, a creature carrying a shovel positive aspects an experience die on the verify.

Terminated Teleporting. Teleportation spells forged in Ostium have a most vary of 500 ft.

Endless Endings​

Souls shuffled off from the mortal coil by no means escape Ostium. Instead once they perish they turn into undead. Some keep housed inside their bones or corpses (as senseless skeletons or zombies), or rise anew as a knight of the spade. Those who attempt to go additional, to see extra, to go the place nobody else has—adventurers principally—are let unfastened from their mortal stays and turn into ghosts within the Explorer’s League.

Ethereal Explorers. There are signposts of a form in Ostium, or moderately beside or maybe round it. In the Ethereal Plane members of the Explorer’s League work exhausting to keep up ethereal waysigns with exact directions to others prefer it, offering the one dependable technique of traversing the dimension. While a creature is ready to see throughout the Ethereal Plane, it can’t turn into misplaced in Ostium.

See Ghosts. A creature carrying a shovel can see ghosts in Ostium even when they’re on the Ethereal Plane, and positive aspects an experience die on Perception checks made towards them.

Many Mazes​

The realm of Ostium is mazes inside mazes inside mazes inside mazes advert infinitum, a lot of them made all of the extra difficult by newly excavated routes and collapses barring passage ahead. Each maze nonetheless has a coronary heart nonetheless, normally fiercely protected by a caravan (containing 2d4+2 NPCs of a most particular person CR equal to 1/4 or lower than the get together’s common stage), aberration, or monster that defends it with their lives. Within these locations there’s all the time an merchandise of nice energy, and as soon as conquered or accepted by its inhabitants PCs can use the center of a maze as a haven.

Winding Ways​

Countless disreputable cartographers, deceitful explorers, and duplicitous retailers promote maps for Ostium—most of that are inauthentic. True maps bought for the dimension are nearly by no means correct for greater than a decade and the waysigns left in plain sight by earlier vacationers are not often there once they return. Adventurers trying to traverse this troublesome aircraft should navigate by the age of the development close by (utilizing History checks), with the assistance of the Explorers League that also yearns to know this place, or by go away of the Court of Spades.

If solely there was a dungeon-themed Level Up guide to actually take advantage of out of Ostium…