I love me a good sentient magic item. The conflict and tension that arises between object and bearer can be nothing short of gripping when told correctly. As with all other things, it can be the stuff of nightmares when told poorly. One of the things I’ve always wanted to do is tell a largely underwater story that revolves around artifacts, kingdom expansion, and relies heavily on the bizarre Greek stories of the sea. With that in mind, it only makes sense that when I see the storied warhammer Whelm, I sometimes read it as Whelk.
If you are not familiar with Whelm, it is one of the artifact weapons from the lost dungeon of White Plume Mountain. It imparts a desire to stay within the confines of the mountain, and to slay the bejeezus out of giants and goblinoids. It is a returning weapon, meant to be thrown and magically appear at the feet of the hurler, and it also launches crippling shockwaves. In a fun twist, it also carries a hidden legacy as a bloody weapon wielded by a fearsome dwarven vampire.
Whelk, on the other hand, is a sentient shield given will by ancient cyclops smiths at the great forges along the volcanic trenches of the deep ocean.
Armor (shield), artifact (requires attunement while completely submerged in water)
Whelk is a shield crafted to resemble the shell of the predatory sea slug of the same name, and one of three items crafted by the cyclopean brothers Arges, Brontes, and Steropes. Whelk only grants its abilities while completely submerged in water, save for remaining indestructible unless destroyed through the specified means.
You gain resistance to acid damage, and a +1 bonus to AC and saving throws. This bonus is in addition to shield’s normal bonus to AC. If you are out of the water and bearing Whelk when the moon is visible in the night sky, you long for the open sea while you remain attuned to the shield. You may not take the Dash, Disengage, or Dodge action, and have disadvantage on ability checks while you can see the moon and are not submerged.
Acidic Plume. You can use an action to plant your shield and have a cloud of acid billow forth. Creatures other than you within 5 feet of you must succeed on a DC 15 Dexterity saving throw, suffering 2d8 acid damage on a failed saving throw, or half as much on a successful saving throw. This damage increases to 3d8 if the creature is an aberration or fiend. You gain half of the total damage dealt to all creatures as temporary hit points. Once used, this property can’t be used again until Whelk is purified during an uninterrupted cleansing ritual that takes no less than one hour to complete.
Deep Sea Hunter. While you bear Whelk, you are aware of the presence of aberrations and fiends within 60 feet of you. You have advantage on saving throws against being charmed or frightened.
Whelk can cast hex on a creature it chooses once per day. It decides when to cast the spell and maintains concentration on it so that you don’t have to.
Secrete. You can use an action to place Whelk against an object and secrete a corrosive acid to weaken objects. When you do so, you have advantage on your next attack against the object, and ignore any damage threshold the object might possess for that attack.
Sentience. Whelk is a sentient lawful neutral shield with an Intelligence of 12, a Wisdom of 17, and a Charisma of 17. It has hearing and darkvision out to a range of 120 feet.
The shield communicates telepathically with its wielder and can speak, read, and understand Aquan. It can also speak with aquatic animals as if using a speak with animals spell, using telepathy to involve its wielder in the conversation.
Personality. Whelk‘s purpose is to seek out and destroy the aberrant and fiendish kingdoms of the sea. It also seeks to serve and protect the merfolk kingdoms against all enemies. Conflict arises if the bearer fails to destroy aberrations and fiends, or to protect merfolk.
Whelk is single-minded in all endeavors. Once Whelk has decided upon a course of action, it will do all in its power to see that action through to completion.
Destroying the Shield. The only way to destroy Whelk is to melt it down in the volcanic sea vents where it was created. It must remain in the vent for ninety-nine years before it is finally consumed.