This slender piece of white chalk is held in a steel handle, and any attempt to remove it from its handle proves fruitless. The handle has a red button on its underside. Created by the Keeper of Secrets as an implement of destruction, this item's power was greatly diminished when its mistress was sealed away. Recovered by a powerful angel who was irreparably injured, the chalk was imbued with a second sentience through that angel's sacrifice, which has now been crushed under Tinker's esoteric might.

Sentience. The Demiplanar Chalk is a sentient lawful evil item with an Intelligence of 30, a Wisdom of 22, and a Charisma of 25. It has hearing and truesight out to a range of 120 feet.

Although the item is capable of communicating telepathically with its wielder, as well as speak, read, and understand all languages, it always chooses inaction, for reasons only it knows.

Personality. An inscrutable and deadly nagpa named Tinker lives inside this item, and is the only inhabitant capable of communicating through it. It bides its time, waiting for something beyond comprehension. It revels in the death of the item's former secondary inhabitant, the solar Familiar.

Dormant

Even when not attuned to this item, any person holding it has access to the following abilities:

• You can use an action to draw a doorway in the air with the chalk, whereupon the doorway opens, casting the demiplane spell in your space. Once the chalk has been used this way, it can't be again for one hour. Time spent in demiplanes doesn't count towards recharging this ability. You can't connect the shadowy door to a demiplane that wasn't created with this chalk.
• While inside a demiplane created with this chalk, you can use an action to push the red button on its handle and cast the plane shift spell without requiring components, but you can only use the spell to send willing targets to a teleportation circle on the Great Hunt Material Plane, the sigil of which you must know.

While attuned to this item, you gain the following additional benefits:

• You have advantage on saving throws made to resist being banished to other planes of existence.
• You can use a bonus action to teleport the chalk to your pocket, or to your hand, or to a similar location on your person.

Awakened

When Tinker's Demiplanar Chalk reaches an awakened state, it gains the following properties:

• You can transform the chalk into a knife blade as a bonus action, or return it to chalk form in the same way. While in the form of a knife blade, you can wield this item as a magic dagger with the following properties:

When you hit an attack with this weapon against a creature you are grappling, that hit is a critical hit, and all attacks made with this dagger against objects are critical hits. As an action while holding it, you can cast the dimension door spell, or instead, you can make an Intelligence (Arcana) check with a DC of 20. On a successful check, you cast the gate spell, with the destination chosen at random by the DM. If the result of your check was 30 or greater, you choose the destination instead. Once you cast a spell from this item in dagger form, you can't do so again until you finish a long rest.

• You can use the chalk to cast passwall, requiring no verbal or material components. Once you do so, you can't use this property again for an hour.

Exalted

When this item reaches an exalted state, it gains the following properties, as the shackles of Familiar's influence are killed off and its true potential is unleashed: 

• The weapon permanently transforms into its dagger form, and you can use the properties of the weapon when it is in the form of a dagger, and the abilities gained from the dagger form can be used at will, without requiring long rests between uses.
• You can use the weapon to unleash an arcane cataclysm as an action. When you do so, you conjure an orb of magical energy that plumets to the ground at a point you can see within one mile of you. Each creature in a 40-foot-radius sphere centered on that point must make a DC 26 Dexterity saving throw, taking 71 (11d12) force damage on a failed save or half as much damage on a successful one. The area of the arcane burst then acts as an antimagic field for 1 hour. The Keeper of Secrets and spells she casts are unaffected by that field. Once you use the weapon in this way, it can't be used to create an arcane cataclysm until the Keeper of Secrets takes a long rest.
• You learn the eldritch blast cantrip. Intelligence is your spellcasting ability for it, and when you hit with one of the blasts, you can add your Intelligence modifier to the damage dealt.

Notes: Advantage: Saving Throws, Eldritch Blast: Bonus Damage