Tempest in a Bottle! (5e Equipment)
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Wondrous Item, artifact (Requires attunement)
The jar attached to this ornate diamond-encrusted necklace has a black, swirling storm cloud filling it to the brim, trying to escape it. Occasionally, a bird-like face and several swirls of tiny feather-shapes can be seen hidden within the clouds and lightning. The inside of the jar is riddled with scratch marks, and the face within it is in a perpetual rage. In reality, it's the captured body of a living Elder Tempest. As part of the process involved in making this item, the soul of the Tempest is bound to it.
Dexterity Increase. While wearing this necklace, your Dexterity score changes to 28 granted by this necklace. This property has no effect on you if your Dexterity without the necklace is equal to or greater than the necklace's score.
Hasted Form. While wearing this necklace, your speed is doubled, you have advantage on Dexterity saving throws, and you gain an additional action on each of your turns. This action can be used only to take the Attack (one weapon attack only), Dash, Disengage, Hide, or Use an Object action. While under this effect, you can't be affected by the haste spell or the Nyan's Light Speed Dash spell. If your attunement to the Artifact ends, you can't move or take any actions for a minute, and gain 1 level of exhaustion.
Shapechange. While wearing this necklace, you can use an action to cast shapechange, turning into an Elder Tempest. When you do so, your concentration on the spell can't be broken as a result of taking damage. Once you have done so once, you can't do so again until you finish a long rest.
Fury of the Tempest. This necklace is cursed, and attuning to it extends the curse to you. As long as you remain cursed, you are unwilling to part from the necklace, keeping it within reach at all times. You have disadvantage on attack rolls while you are not wearing the necklace. If you use the shapechange feature of this necklace while you are cursed in this way, you can't willingly drop concentration on the spell. If the spell lasts the full hour, the true polymorph spell is cast on you (DC 22) before your form reverts, turning you into an Elder Tempest on a fail. If you stay transformed because of this, you become possessed by the soul of the Elder Tempest contained within the Artifact. While possessed in this way, the Elder Tempest controls your actions. If you stay transformed for the full hour duration of true polymorph, you cannot be freed from the Tempest's control by any means short of a wish spell or divine intervention. If you are somehow freed from the Tempest's control, or the Tempest is reduced to 0 hit points, the true polymorph spell ends on you. An identify spell reveals that the necklace is cursed, but fails to reveal the nature of the curse. A legend lore spell reveals that the curse originated from the item's initial construction being incredibly subpar, leaving the item unstable, but fails to reveal the nature of the curse. At the DM's discretion, there may be a way to effectively "fix" the item, removing the curse and making the item harder to destroy (As a normal Artifact would be) through methods of the DM's choice, such as through the wish spell or by finding a way to kill the Elder Tempest inside (Without letting it out). If the curse is removed, the item loses this property and the Shapechange property.