Thassa wields Dekella, a two-pronged weapon gifted to her by Purphoros. When the god of the sea bestows her weapon on a mortal, it's often so they might work her will far from the ocean, right some wrong affecting those she'd prefer not to harm, or give a mortal a glimpse of her terrible responsibilities.
Thassa's signature weapon thrums with the icy currents of the deep ocean. This weapon functions as a trident that grants a +3 bonus to attack and damage rolls made with it. When you hit with an attack using the bident, the target takes an extra 2d10 cold damage.
If you are a worshiper of Thassa, you gain all the following benefits for which you have the required piety:
Piety 10+ You can breathe underwater, and you gain a swimming speed of 60 feet.
Piety 25+ The bident has 1 randomly determined Artifact Properties; Minor Beneficial Properties property.
Piety 50+ The bident has 1 randomly determined Artifact Properties; Major Beneficial Properties property.
If you aren't a worshiper of Thassa, the bident has 1 Artifact Properties; Minor Detrimental Properties property and 1 Artifact Properties; Major Detrimental Properties property, both randomly determined.
See "Artifacts" in chapter 7 of the Dungeon Master's Guide for details on randomly determined properties.
The bident holds the power to command the waves and its creatures. As an action, you can change the condition of the sea within 1 mile of you, creating strong winds and heavy rain that cause violent waves (see "Weather at Sea" in chapter 5 of the Dungeon Master's Guide) or calming a storm. In either case, the unnatural weather lasts for 1 hour before returning to normal. Once used, this property of the bident can't be used again until the next dusk.
Additionally, you can cast the dominate monster spell (save DC 18) from the bident, but only on beasts and monstrosities that have an innate swimming speed. Once used, this property of the bident can't be used again until the next dusk.
You can cast the true polymorph spell (save DC 18) from the bident, but you must cast it on a creature to turn it into a kind of creature that has an innate swimming speed. Once used, this property of the bident can't be used again until the next dusk.
To destroy the bident, it must be heated by the breath of an ancient red dragon and then, while still hot, immersed in the Tartyx River.
If a weapon has the thrown property, you can throw the weapon to make a ranged attack. If the weapon is a melee weapon, you use the same ability modifier for that attack roll and damage roll that you would use for a melee attack with the weapon. For example, if you throw a handaxe, you use your Strength, but if you throw a dagger, you can use either your Strength or your Dexterity, since the dagger has the finesse property.
This weapon can be used with one or two hands. A damage value in parentheses appears with the property—the damage when the weapon is used with two hands to make a melee attack.