The PCs were present at Toch'tenocht (The Temple of Lost Dreams) when the keystone fell from the heavens as foretold by the dragon Vermisaracht I, delivering a fragment of the Draconic Prophecy. The keystone is imbued with minor intelligence and the ability to select Wardens and present them with their keys.
The text of the Prophecy sounds as a psychic call when any prospective Warden stands in the energy field emanating from the keystone. A deep voice speaks in Draconic and delivers the following:
“There are Six Locks that shackle the Corruptor in Khyber's womb. She strains at the silvery chains and has nearly slipped her bonds. But locks have keys, and a key that will release a god can also rebolt the lock. Choose your key from the Keystone, Warden."
The Keystone is a massive Siberys Dragonshard that emits a field of light that, when entered by a prospective Warden, reveals a snippet of the Draconic Prophecy and offers a suitable key. Each of the Keys appears as a Dragonmark or as modifications to existing Dragonmarks (if the Warden is a Dragonmarked Heir). There are hundreds of keys within the keystone, but it will only present thirteen different keys, one for each of the current Dragonmarks.
Key of the Healer (Jorasco)
Initial Effect: As an action, you may spend any number of Hit Dice up to your maximum and then roll them. All allies within 30 feet regain twice that number of Hit Points.
6th Level Upgrade: Spend a Hit Die to cast the spell Revivify without expending a spell slot or material component. Instead of the normal 1 hit point they revive at, roll that spent Hit Die and the revived character gains twice that number of Hit Points.
Status: Unclaimed
Key of the Sentinel (Deneith)
Initial Effect: You may spend a Hit Die to cast the Shield spell as a reaction on yourself or any target you can see within 30 feet. If you cast the spell on someone other than yourself, you also gain the benefit of the Shield Spell.
6th Level Upgrade: You may spend a Hit Die to cast Protection from Energy without expending a spell slot or material component. For each additional hit die you spend, you may apply it to two other allies within 30 feet, all with the same damage resistance. The spell still requires Concentration to maintain. When you take damage, you may spend a Hit Die to automatically roll a 20 on the Constitution Save to maintain this effect. You must choose to use this feature before you roll. If the roll still fails, all members currently under Protection from Energy lose the aegis.
Status: Currently in possession of Akuran Thul
Key of the Stalker (Tharashk)
Initial Effect: As an Action, you may spend a Hit Die to give yourself True Seeing for one minute, without expending a spell slot or material components.
6th Level Upgrade: As an Reaction, you may spend a Hit Die to make one creature Vulnerable to a single attack. They take half again as much damage from this attack.
Status: Currently in possession of Akuran Thul
Key of the Scribe (Sivis)
Initial Effect: As an Action, you may spend any number of Hit Die to draw a magical sigil one target can see. If the target fails a DC 15 Wisdom Save, it takes psychic damage equal to 2d6 + the number and type of Hit Dice you spent. If the creature Saves, it takes half damage.
6th Level Upgrade: You may spend a hit die to tap into the Draconic Prophecy and cast the spell Divination without expending a spell slot or material components. All rules for the Divination spell apply.
Status: Currently in possession of Eelix
Key of the Traveler (Orien)
Initial Effect: As an Action, you may spend a Hit Die to Teleport yourself and one willing creature 60 feet in any direction. For each additional Hit Die spent, teleport two more characters. All characters go to the same location.
6th Level Upgrade: You may spend a hit die to cast Teleportation Circle without expending a spell slot or material components. For one hit die, this casting connects to a random teleportation circle. For two hit die, you can go to a specific teleportation circle that you know, and for three hit die, you can go to any teleportation circle, even if you do not know the unique sigils to connect to it.
Status: Currently in possession of Akuran Thul
Key of the Crafter (Cannith)
Initial Effect: As an Action spend a Hit Die to imbue any standard melee or ranged weapon you can see with a magic bonus to attack and damage equal to your Proficiency. This in effect functions like Expertise on Attack rolls and allows for Proficiency bonus to damage rolls as a magical bonus that stacks with other magical bonuses. This effect lasts for one minute.
6th Level Upgrade: You may spend a Hit Die to imbue any weapon, including magic attack devices (staffs, wands, etc) with your Proficiency bonus as described above. In addition to this, you may also change the damage type of that weapon to another type. You can change a sword's normal slashing damage to Fire, or a Wand of Magic Missiles to Ice, allowing it to bypass immunities or resistances.
Status: Currently in possession of Akuran Thul
Key of the Seer (Medani)
Initial Effect: As a Reaction, you may spend a Hit Die to influence Fate. Spend your Hit Die and then roll it. Either Add or Subtract that number for any Attack Roll or Saving Throw for a creature you can see.
6th Level Upgrade: As an Action, spend a Hit Die to cast Death Ward on yourself or an ally without expending a spell slot or material components. The spell lasts for 8 hours.
Status: Currently in possession of Alexios
Key of the Necromancer (Vol)
Initial Effect: As an Action, spend a Hit Die to cast the spell Animate Dead as a 3rd Level Spell without expending a spell slot or material components (although you still need bodies). For each additional Hit Die used for this effect, animate two additional creatures.
6th Level Upgrade: As an Action, spend a Hit Die to cast Blight as a 4th Level spell without expending a spell slot or material components. For each additional Hit Die spent on this casting, increase the caster level of Blight.
Status: Unclaimed
Key of the Beastmaster (Vadalis)
Initial Effect: As an Action, spend a Hit Die to cast Conjure Animals as a 3rd Level Spell without expending a spell slot or material components. The spell still requires Concentration to maintain. When you take damage, you may spend a Hit Die to automatically roll a 20 on the Constitution Save to maintain this effect. You must choose to use this feature before you roll.
6th Level Upgrade: As an Action, spend a Hit Die to cast Dominate Beast as a 4th Level Spell without expending a spell slot. For each additional Hit Die spent on the initial casting, cast the spell at a Higher Level. The spell still requires Concentration to maintain. When you take damage, you may spend a Hit Die to automatically roll a 20 on the Constitution Save to maintain this effect. You must choose to use this feature before you roll.
Status: Unclaimed
Key of the Tempest (Lyrandar)
Initial Effect: As an Action, spend a Hit Die to cast Thunderwave as a 3rd Level Spell without expending a spell slot. For each additional Hit Die spent, increase the damage by 1d8. Spell Save DC is 15.
6th Level Upgrade: As an Action, spend a Hit Die to cast Wind Wall without expending a spell slot or material components. In addition to the 3d8 bludgeoning damage taken by anybody within the area of the wall, they also take an additional 2d6 lightning damage. Spell Save DC is 15.
Status: Currently in possession of Veton
Key of the Warder (Kundarak)
Initial Effect: As an Action, spend a Hit Die to cast Magic Circle as a 3rd Level Spell without expending a spell slot or material components. For each additional hit die spent, increase the casting level and duration as listed in the spell description.
6th Level Upgrade: As an Action, spend a Hit Die to cast Globe of Invulnerability as a 6th level spell without expending a spell slot or material components.
Status: Currently in possession of Ding Silverhand
Key of Shadows (Phiarlan & Thuranni)
Initial Effect: As an Action, spend a Hit Die when you are in Dim Light or Darkness to become Invisible. This invisibility lasts until you move, take an action, or a Reaction. For each additional Hit Die spent, this effect can be given to another ally.
6th Level Upgrade: As an Action, spend a Hit Die to cast Seeming as a 5th level spell without expending a spell slot.
Status: Unclaimed
Key of Hearth (Ghallanda)
Initial Effect: As an Action, spend a Hit Die to cast Tiny Hut without expending a spell slot or material components. For every additional Hit Die, four more people can be accommodated. For an additional Hit Die, you can add a banquet to feed you and the maximum number of accommodated guests inside the Hut. The hut and any food or water that is not consumed disappear after 8 hours.
6th Level Upgrade: The banquet within the Tiny Hut is magically converted into the spell Hero's Feast without expending a spell slot or material components. No additional Hit Die need to be spent.
Status: Currently in possession of Zarth d'Orien