Ith-Narmant's Lantern

This black metal lantern was crafted by the artificer warlocks of Ith-Narmant, the master of shadows, chill, and solanaceae. It has a black leather hood made from humanoid skin, is always cold to the touch and never exudes heat even while burning. It shines an eerie, dim, unnatural bluish light in a radius of 50 feet.

The special oil used in Ith-Narmant's Lantern will burn for up to 4 hours or 24 turns and can only be made with an elaborate ritual, a sacrifice and the blessing of a cleric of Ith-Narmant. If utilizing this oil as a thrown weapon, it will inflict 1d8 cold heat damage on a successful hit and 1d4 cold heat damage on the following two rounds (this can only be prevented with resistance to both magical fire and magical cold).

Animals will never freely enter or stay in the light of Ith-Narmant's Lantern. Characters and monsters of non-chaotic alignment must make a saving throw against magic to enter or stay in the lantern's light. If they fail, they can still enter or stay inside the illuminated area, but will feel very uncomfortable, get -2 on all rolls and try to escape the light after a certain number of rounds (Wisdom score determines the maximum number of rounds for characters, double hit dice does the same for monsters). They cannot try to re-enter the light before one turn has passed.

Ith-Narmant's Lantern can be lit and used by any class. It grants the shadow tunnel ability to everyone in its light. Shadow tunneling allows entering a shadow and emerging from another shadow. Both shadows have to be cast by the blue rays of the lantern, so only shadows from objects or living things that are inside the light radius of the lantern qualify. The destination shadow has to be chosen at the time of entering. If this shadow does not qualify anymore when trying to emerge from it, the traveller is lost in the shadow realm (see table result 6). The complete shadow tunneling takes three rounds: one for entering, one for travelling, and one for emerging.

Shadow tunneling actually means travelling through the shadow realm of Ith-Narmant, and comes not without dangers. Every time when shadow tunneling, make an unmodified d20 roll. On a 1, there are complications (see table).

Shadow Tunneling Complications (1d6):

1. Receive a demonsign of Ith-Narmant. This can take many forms, but most commonly results in a pitch black mark on the skin that does not reflect any light. These signs are recognized by demon hunters and inquisitors. 
2. You lose a valuable item in the shadow realm.
3. A Shadow emerges along with the traveller (see S&W Complete, page 112).
4. Lose your own shadow for 1d6 days. During this time, you cannot regain lost hp.
5. You are chilled to the bone and temporarily lose 1d6 Strength. If this brings your Strength to 0, you die and are transformed into a Shadow (see S&W Complete, page 112). Your lost Strength returns after 9 turns. If you die before that happens, you are also transformed into a Shadow.
6. If you do not yet have a demonsign, you receive one and emerge normally. Otherwise, if you are already marked with a demonsign of Ith-Narmant, you do not emerge from, but are instead lost in the shadow realm of Ith-Narmant. Your friends might try to come and rescue you, if they are brave or foolish enough.

Originally written for the magic item contest over at Tenkar's Tavern, for use with Swords & Wizardry Complete - but of course you can easily use it with any other fantasy RPG. If you're using it with the DCC RPG, I'd suggest to roll on the corruption tables when a character receives a demonsign; and you'll find a Shadow monster on page 425 of the rulebook.

You can find a bit more information about Ith-Narmant in Crawl!#7, along with another of his magic items, the Shadowsword of Ith-Narmant, including DCC RPG stats.