Seal of the Skyward Stair | Free Adventure for D&D and Pathfinder 2e

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Seal of the Skyward Stair - D&D 5e

Below are the details you need to run this adventure. However, the game master is encouraged to customize it slightly for their group and ongoing campaign. Consider questions such as the following:

Where will this adventure take place in your world?
Should you change any of the location names to make them better fit your campaign setting?
Should you increase or decrease the loot, including adding or removing magic items?
Should you adjust any of the encounters to better fit the power level of your players and their characters?

Game Master Notes

Level. This adventure is designed for a group of four to six level-11 characters.

Creatures. This adventure features the following creatures: nimbus elemental.

Resting. It’s expected that the party will not need to take any long rests in this adventure, though they may need a short rest if the characters encounter bad luck.

Loot. This adventure contains the following treasure: helm of telepathy and deck of illusions.

Divine magic has sealed the staircase to the sky palace ever since a void corruption began leaking through cracks in the planar fabric. Once a place of serenity and celestial convergence, the glade has become a place of magical instability. The four arcane pool portals—ancient, sacred conduits of astral energy—now churn with tainted essence, their waters flickering with sickly light and pulsing with erratic magical surges. Each portal feeds the growing disturbance at the heart of the glade, fueling something far more dangerous than mere corruption.

The Corrupted Glade

The once-serene glade—where azure pools shimmered and soft moss blanketed the ground—has become a warped nexus of magical devastation. The grand stairway leading into the clouds now stands sealed, blocked by an impenetrable barrier of arcane force. This energy pulses from glowing runes inscribed on the archways that rise from each shimmering pool. At the glade’s center, a vortex of arcane entropy churns violently, twisting the air and lashing out with tendrils of black-green lightning that arc between the portals, spreading corruption. Twisted reflections ripple across the waters—flashes of a burning sky-castle or distorted echoes of the characters themselves—while unstable motes of light swirl chaotically, pulsing like frantic heartbeats and flickering through erratic hues. The very weave of magic here feels frayed and disrupted.

Creatures. Three nimbus elementals lie dormant within two of the corrupted pool portals.

Pool Portal Exterior. Moss-covered stone archways framing each pool portal bear the chiseled markings of ancient runes. Characters can translate them with either a successful DC 11 Intelligence (History) or (Religion) check. The northwest pool portal translates to “Court of the Silent Pool”; the northeast pool portal translates to “The Echoglass Pool”; the southeast pool portal translates to “Pool of Inner Knowing”; the southwest pool portal translates to “The Sacrificial Pool.”

Pool Portal Interior. The characters must enter all four pool portals, but only after each succeeds on a DC 15 Intelligence (Arcana) check. Once inside, different challenges await them, which they must pass to purify the pool portal. Time stands still back in the Material Plane as the characters are in the pool portals. Once inside, they cannot cast spells or use character abilities due to the powerful magic suppressing them. Failing a portal challenge will kick the characters out. They can reenter the portal after three rounds, and the DC for the Intelligence (Arcana) check to reenter increases by 1 to a maximum of 20.

Roleplaying Notes.

· The nimbus elementals are diplomatic, have great empathy and emotional restraint, and communicate only through telepathy. Each character hears their own voice when the elemental speaks to them, but shaped by a different tone—older, younger, or shadowed by doubt.

· When a character lies or shows emotional instability, the elemental’s form becomes more chaotic—sparks of lightning ripple through their mist, or their glow dims in colorless pulses. When characters are honest, the elementals hum warmly, and celestial starlight glimmers inside them.

· The reflections within the Echoglass Pool mimic only the negative aspects of a character’s personality. The reflections mock and gaslight the characters, saying anything they can to cause doubt, tension, and strife.

· The disembodied voice within the Sacrificial Pool is calm and almost hypnotic, but with a weighted sorrow. The voice fills the air rather than coming from any direction, its arrival accompanied by a pressure on the mind.

Encounter Notes.

· When the characters enter this portal, three dormant nimbus elementals awaken and transport them to a starlit void where a council of ancient, silent judges awaits. Each character must justify their right to ascend or answer probing questions about their morality, identity, or leadership. Honest answers please the court, while lies, aggression, or loss of composure cause the portal to reject the entire group. If all characters respond truthfully, the character with the most compelling answers (at the GM’s discretion) receives the helm of telepathy.

· This portal leads to a claustrophobic realm of mirrors, where distorted reflections whisper lies drawn from the characters’ fears or secrets. These reflections may also sow distrust by accusing party members of hidden motives. Each character must succeed on a DC 15 Insight, Persuasion, Intimidation, or Investigation check (player’s choice) to silence the reflection, with up to three attempts allowed. Three failed checks will eject the group from the portal.

· Upon entering, each character faces a vision drawn from their fears, regrets, or inner flaws. A DC 12 Insight check may help interpret it, but how the character chooses to confront it is open-ended. Success may come through asserting identity (Charisma), enduring pain (Constitution), analyzing the illusion (Investigation), or drawing on faith (Religion). Each character has three attempts, and failure by any one character will expel the entire party. The character who demonstrates the most meaningful personal growth (at the GM’s discretion) receives a deck of illusions.

· Each character receives a demand to sacrifice something deeply personal—magic, vitality, memories, cherished items, or relationships. Characters may choose to accept, negotiate, or refuse, with refusal resulting in immediate ejection. Alternatively, a character can volunteer to sacrifice both their offering and someone else’s. The first to do so selflessly receives a blessing, and both sacrifices are miraculously restored upon exiting the portal.

Arcane Surgestorm

Magical trap (Complex trap, level 11-15, deadly)

Description. At the center of the glade, a pulsing knot of blueish-green light no larger than a human heart hovers above moss, surrounded by flickering motes like dying stars. A low hum presses on the skin and mind, as if the glade holds its breath. Its core shivers, sending violent streaks of lightning toward the corrupted pools. The motes spiral outward, and the hum builds to a psychic thrum as the light spreads in a 10-foot radius—the arcane surgestorm awakens, sensing a presence.

Trigger. The arcane surgestorm is dormant before the characters enter the glade, but their presence causes the trap to activate.

Initiative. The arcane surgestorm acts on initiative counts 20 and 10.

Active Elements

Arcane Surge (Initiative 20). The arcane surgestorm pulses its magic within its radius. Any creature within the storm’s radius must succeed on a DC 16 Constitution saving throw, taking 3d6 force damage on a failed save, or half as much on a success. If a creature fails the save by 3 or more, they gain 1 level of arcane sickness. These effects stack. On level 1 of arcane sickness, the creature has disadvantage on concentration checks and Intelligence (Arcana) checks. On level 2 of arcane sickness, the creature’s hit point maximum is reduced by one-quarter. On level 3 of arcane sickness, at the start of each turn, the creature must roll on the Wild Magic Surge table or trigger a magical mishap (at the GM’s discretion).

Arcane Feedback (Initiative 10). The arcane surgestorm lashes out at any arcane energy sources it detects. If a creature within 60 feet has an active magical effect on it (such as mage armor, shield of faith, fly, etc.), it must make a DC 15 Charisma saving throw or take 4d6 psychic damage as the magic turns against it, crackling with arcane static. On a failed save of 3 or more, the magical effect ends prematurely. On a successful save, the creature takes half damage.

Dynamic Element

Arcane Surgestorm Movement. Each time an active element occurs, the arcane surgestorm increases its spread by a 5-foot radius, up to a maximum of 60 feet. Additionally, the arcane surgestorm can move up to 15 feet.

Reality Shear. Whenever the arcane surgestorm expands, roll 1d6. On a 5 or 6, a tear in reality forms at a random point within the storm’s radius for 1 minute. Creatures that start their turn or move within 5 feet of a tear must succeed on a DC 16 Dexterity saving throw or be partially phased, taking 2d6 force damage and becoming invisible and incapacitated until the start of their next turn, lost between planar layers.

Constant Element

Arcane Disruption. Casting a leveled spell within the arcane surgestorm requires an (Intelligence) Arcana check. The DC equals 12 plus the spell’s level. On a failure, the spell fails to cast, but the caster does not waste the spell slot. A failure of 3 or more still casts the spell; however, the spell is reversed or targets the caster (at the GM’s discretion).

Charged Terrain. The ground inside the surgestorm holds a magical charge. Creatures who don’t move at least 5 feet during their turn must succeed on a DC 14 Constitution saving throw or take 2d4 lightning damage as the arcane current builds beneath them. A failure of 3 or more also stuns the creature until the end of its next turn, during which it becomes immune to the charged terrain effect.

Countermeasures

The arcane surgestorm ends immediately when the characters purify all four corrupted pool portals.

Spells such as dispel magic may temporarily halt the arcane surgestorm’s active and dynamic elements for 1 round, but they cannot suppress it permanently.

Scattered across the glade are four ancient glyphs partially buried in moss. A character who succeeds on a DC 15 Wisdom (Perception) check can locate one of the glyphs. Interacting with it requires a DC 13 Intelligence (Arcana) check, which suppresses the arcane surgestorm’s active and dynamic elements for 1 round and reduces its radius by 10 feet. Each glyph only has enough power for one use.

The storm pulses according to an unstable geometric sequence. A character can become aware of a pattern with a successful DC 14 Intelligence (Investigation) check. Following this with a successful DC 13 Intelligence (Arcana) check will allow them to identify and disrupt the pulse pattern, delaying the next arcane surge by 1 round. They can do this once every 3 rounds.

Conclusion

Once the characters purify all four pool portals, the seal over the skyway stair dissipates, and the characters are free to head up toward the sky palace.

Seal of the Skyward Stair - Pathfinder 2e

Below are the details you need to run this adventure. However, the game master is encouraged to customize it slightly for their group and ongoing campaign. Consider questions such as the following:

Where will this adventure take place in your world?
Should you change any of the location names to make them better fit your campaign setting?
Should you increase or decrease the loot, including adding or removing magic items?
Should you adjust any of the encounters to better fit the power level of your players and their characters?

Game Master Notes

Level. This adventure is designed for a group of four level-11 characters.

Creatures. This adventure features the following creatures: nimbus elemental.

Adventure Difficulty. The party can expect to encounter one low encounter in this adventure.

Loot. This adventure contains the following treasure: helm of zeal and deck of illusions.

The Corrupted Glade Low 11

Creatures. Two nimbus elementals lie dormant within two of the corrupted pool portals.

Pool Portal Exterior. Moss-covered stone archways framing each pool portal bear the chiseled markings of ancient runes. Characters can translate them with either a successful DC 25 Society or Religion check. The northwest pool portal translates to “Court of the Silent Pool”; the northeast pool portal translates to “The Echoglass Pool”; the southeast pool portal translates to “Pool of Inner Knowing”; the southwest pool portal translates to “The Sacrificial Pool.”

Pool Portal Interior. The characters must enter all four pool portals, but only after each succeeds on a DC 28 Arcana check. Once inside, different challenges await them, which they must pass to purify the pool portal. Time stands still back in the Material Plane as the characters are in the pool portals. Once inside, they cannot cast spells or use character abilities due to the powerful magic suppressing them. Failing a portal challenge will kick the characters out. They can reenter the portal after three rounds, and the DC for the Arcana check to reenter increases by 1 to a maximum of 30.

Roleplaying Notes.

Encounter Notes.

· This portal leads to a claustrophobic realm of mirrors, where distorted reflections whisper lies drawn from the characters’ fears or secrets. These reflections may also sow distrust by accusing party members of hidden motives. Each character must succeed on a DC 30 Intimidation, Perception, or Diplomacy to silence the reflection, with up to three attempts allowed. Three failed checks will eject the group from the portal.

· Upon entering, each character faces a vision drawn from their fears, regrets, or inner flaws. Success may come through asserting identity (Charisma), enduring pain (Constitution), analyzing the illusion (Perception), or drawing on faith (Religion). Each character has three attempts, and failure by any one character will expel the entire party. The character who demonstrates the most meaningful personal growth (at the GM’s discretion) receives a deck of illusions.

Arcane Surgestorm Hazard 11

Magical, Trap, Complex

Stealth DC 36

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Disable Dispel Magic (Counteract DC 33) or DC 30 Arcana to disable the glyphs powering the storm

Mortal Presence [reaction] Trigger. The arcane surgestorm is dormant before the characters enter the glade, but their presence causes the trap to activate. Effect. The ground becomes magically charged and deals 1d12 electricity damage to any creature that does not move on its turn. The trap then rolls initiative.

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Routine [one action] The arcane surgestorm pulses its magic within 60 feet. Any creature within the storm’s radius must succeed on a DC 30 Fortitude save, taking 1d12+15 electricity damage on a failed save. On a critical failure, they gain 1 level of arcane sickness. These effects stack. On level 1 of arcane sickness, the creature has a -2 penalty on checks made when casting spells. On level 2 of arcane sickness, the creature’s hit point maximum is reduced by one-quarter. On level 3 of arcane sickness, at the start of each turn, the creature must has a 50% chance of losing a spell slot, regardless of whether it casts a spell.

Conclusion

Once the characters purify all four pool portals, the seal over the skyway stair dissipates, and the characters are free to head up toward the sky palace.