As part of my converting Stoneheart Valley and Sword of Air, I've been working on the chapter Into the Plane of Shadow. I just did a 5e version of the Hand of Knem Koth. It's so fun, but I can't share with any of my other friends, because they all are going to play in the campaign, and I don't want to spoil anything.
Hand of Knem Koth
Wondrous item, artifact (requires attunement)
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Mark of Undeath. When a character first becomes attuned to the item, a series of changes falls over the character.
Finally, because of your brush with undeath and shadow, you are immune to disease while attuned to the artifact.
Spellcasting. If the hand of Knem Koth wishes, you can use an action to cast the chill touch cantrip.
In addition, you can cast one of the following spells: animate dead, commune, and darkness. Once you cast one, roll a d6. On a 1-5, you cannot cast that spell again until you take a long rest.
Dimensional Anchor. Anyone attempting to teleport or use planar travel of any king within 200 feet of the bearer of the hand of Knem Koth must make a DC20 ability check, using their spellcasting modifier, in order to do so without the hand’s permission.
Gate Mastery. The bearer can inscribe the mark of Knem Koth upon any permanent magical gate, which allows the attuned bearer to control who passes between the planes that the gate connects. The mark remains until dispelled by the bearer of the hand as an action, or until a new owner attunes to the hand of Knem Koth.
Sentience. The hand of Knem Koth is a sentient chaotic evil wondrous item with an Intelligence of 20, a Wisdom of 15, and a Charisma of 19. It has hearing and darkvision, in both natural and magical darkness, and communicates via telepathy. A creature can attempt a DC20 Intelligence saving throw to block out the telepathic communications from the hand; on a success, they are immune to it’s communication for 24 hours.
Personality. The hand of Knem Koth whispers to those around it in their minds. The hand has a single purpose: be reunited with its other parts and resurrect the lost, dead god Knem Koth.
It despises living things, treating them as, at best, tools to be used. It delights in suffering and darkness, and seeks also the darkening of the natural world.
The hand of Knem Koth can use an action to cast suggestion on a creature within 30 feet of it that it can see. The magical coercion forces the creature to take up the hand and attune to it. It can also cast counterspell should any attempt to use remove curse on it’s attuned wielder.
Once per day, on any day that the hand of Knem Koth spends in sunlight, magical or otherwise, triggers a conflict between it and its wielder. A conflict also occurs on any day that an attuned wielder attempts to seek the hand’s destruction (see below), attempts to willingly break attunement to the artifact, or if the wielder has spent 7 days without pursuing any of the hand’s goals.
If a conflict occurs, the hand and its attuned wielder make an opposed Charisma check. If the item wins, the hand of Knem Koth demands that the wielder begin pursuing the hand’s goals above all other goals. If the wielder refuses, they must make a DC16 Charisma saving throw. On a failed save, the wielder is charmed by the item for 1d12 hours. While charmed, the wielder must try to follow the item’s commands. If the wielder takes damage, it can repeat the saving throw, ending the effect on a success. Whether the attempt to control its user succeeds or fails, the hand of Knem Koth can’t use this power again until the next dawn.
Destruction. The hand of Knem Koth can be destroyed if an attuned carrier places the hand on an altar of the God Arden, and exposes it to sunlight for 168 hours (1 full week) of direct, natural sunlight. In order to be destroyed, a character must remain attuned to it to suppress its malevolent touch.