Rings of Power

Magic Rings - always fun, always claimed, always tested by PCs donning them.  

Here are three for your games.

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From some online shop.  If you want a prop, buy it!

Ring of the Necromancer

This ring is made of bone and is carved into a skull shape.  It is cold to the touch. 

Attunement - 1 permanent Constitution loss; removing the ring results in immediate unattunement.

The wearer of the ring can control twice the number of undead that their level allows, and wearer-created undead are at maximum hit points when created.

In addition, the wearer's necromancy spells are always at maximum dice rolls.

This ring also has several quirks. The first being that the wearer is vulnerable to cold-based damage, suffering one additional damage die from such attacks, AND cold-based damage always does at least 2 points of damage per die rolled. The second is that all Death Saves are rolled at Disadvantage.  The third is that the wearer cannot be restored to life, regardless of magic, instead rising as a spell-casting wraith, it's spells being whatever was still memorized when the Necromancer wearing it died, the spells replenishing themselves every 24 hours.   Lesser quirks include that normal animals fear the wearer, trying to bolt and pissing everywhere in the wearer's presence, and that the wearer leaves footprints of dead grass and plantlife behind them as they walk - they literally stain the world as they move. 

DM Note: in my world, creating undead rips the spirit or soul from its afterlife, forcing it back into its physical body to animate it.  This is why Necromancy is considered evil, and also why undead hate the living.

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A real ring costing more than I can afford.

Ring of the Lich-King

A platinum band with diamond studs.  

Decades back, heroes (of a sort) battled the Lich-King and removed his hand.  The Wizard among the group placed the hand - with its ring still on a finger - within a protective glass display case.  This case prevents scrying and detection, which means that in the ensuing decades, the Lich-King has yet to find his missing ring.  It goes without saying that some enterprising fool adventurer will discover and remove it from the glass and don it.

Attunement - 1 permanent Constitution loss; the ring won't come off unless the finger is removed.  Doing so leaves a stump that will not grow back, even with a Wish.

The Ring of the Lich-King functions as a ring of spell turning, a (limited) ring of mind shielding, and a ring of wizardry that doubles both first and second level spell capacity for its wearer.  So a third-level wizard (foolishly) donning this ring would be able to memorize 8 first and 4 second level spells, rather than the RAW 4 first and 2 second (damn, 5e hands out spells like candy).

Living wearers are at Disadvantage for all saves.  In addition, nightmares come and go; with each attempt at a long rest, the PC must make a Wisdom save DC 15 or suffer a restless sleep, so gaining none of the benefits of a long rest.  If asked, these nightmares feature a crowned skeletal being actively pursuing the PC in question.

Once donned by a living being, the Lich-King knows and sends undead minions of increasing power to take it back.  This is the limitation of the ring of mind shielding - the Lich-King can (and will) get around it.  Undead target the Ring-wearer above all others, trying to reclaim the Ring for their master.

Should a living being be slain while wearing the Ring of the Lich-King, the being rises as a Wight the next round, completely under the thrall of the Lich-King, making haste to return the ring to its rightful owner.

The world will suffer if this happens.

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A ring from Amazon, so you know its quality!

Viper's Kiss

A silver ring featuring twin viper heads with carnelians in their mouths.  It feels incredibly dry to the touch.

When donned, the ring constricts around the finger and the fangs extend, piercing the skin.  This begins the attuning.  The ring injects a poison into the wearer, and if they make the DC14 Constitution save, the ring-wearer's eyes turn into snake-eyes, their tongue begins forking, and over time, their entire body begins to grow scales, starting at the finger.  This scaling is complete after a year.

Failing the save results in a particularly virulent poison coursing through the wearer's system, and the ring dropping off the finger.  This poison causes the wearer's skin to turn scaly and start dropping off, reducing Charisma (its gross watching someone's skin fall off in bits) and Dexterity (its painful to have skin chafing off) by 2d4 each.

Viper's Kiss provides its wearer with several benefits: immunity to reptile-based poisons; Advantage on saves versus other poisons; can speak with reptiles; reptiles are not immediately hostile to the wearer; the wearer can spit poison as a Guardian Naga.

Along with its benefits, Viper's Kiss also has drawbacks.  Chief among them is that cold and cold weather drop the wearer into a torpor, leaving the wearer effectively stunned in colder temperatures and paralyzed in temperatures below 0.  In addition, every time the PC wearing the ring levels up, they MUST molt, shedding their skin and becoming extremely vulnerable (also cannot wear anything but loose robes due to massive skin irritation).  What becomes of the PC-shaped skins is anyone's guess! 

I am confident a good DM will make sure the PC in question thinks about it....