Urfrost, Blade of Hungering Cold

[Wryte]

Looking for feedback on a sentient weapon I'm creating for one of the major antagonists of my campaign.

Urfrost
Weapon (greatword), legendary (requires attunement by a creature of non-good alignment)

Hundreds of years ago, the frost giant king, Thiazadum, wished upon an efreeti for the power to destroy his enemies. Thus was born Urfrost, the Blade of Hungering Cold. Urfrost's blade is permanently rimed with hoarfrost, which leaves a trail of ice motes in the wake of its strikes. Its handle and crossguard are forged from the bones of an ancient white dragon, and its pommel is a shard of meteorite that still holds the chill of space.
Urfrost grants its wielder a +3 bonus to attack and damage rolls made with it and deals an additional 1d6 cold damage on a successful hit, and has the following additional properties:
* Consume Flames. As a bonus action while holding Urfrost, its wielder can extinguish all nonmagical flames within 30 feet of themself. Additionally, they are resistant to fire damage while holding the weapon, and can use their reaction to become immune to fire damage until the start of their next turn.
* Devour Warmth. Whenever Urfrost deals damage to a creature, the creature must make a Constitution saving throw, suffering all of the following effects of any failed saves:
** DC 20: The creature takes 1d6 cold damage, and its speed is reduced by 10 feet until the end of the wielder's next turn.
** DC 15: The creature takes 1d6 cold damage, and cannot take reactions until the end of the wielder's next turn.
** DC 10: The creature takes 1d6 cold damage, and can take either an action or a bonus action on its turn, not both, until the end of the wielder's next turn.
** DC 5: The creature is petrified, turned into a figure of solid ice as Urfrost steals all the heat from its body.
* Scale. Urfrost resizes itself to suit its wielder, gaining an additional 2d6 slashing damage for each size category it grows above medium.
* Sentience. Urfrost is a sentient chaotic evil weapon with an Intelligence of 7, a Wisdom of 13, and a Charisma of 20. It has hearing and sight out to a distance of 120 feet, and its senses are not obstructed by snow or similar natural phenomena. It does not understand or speak any language but violence and hunger, and communicates with its wielder by transmitting emotions.
* Personality. Urfrost's being is little more than a constant, instinctive hunger to devour heat, which it spreads to its wielder. Its hunger is ceaseless, and can never been satisfied; only tempered. Conflict arises between Urfrost and its wielder if 3 days pass and for each day thereafter that passes without the weapon reducing a living creature to 0 hit points or being plunged into the body of a creature that has been dead for less than a minute. If Urfrost feeds on a fire elemental in this manner, this period is 7 days.
* Cursed. Urfrost was created for Thiazadum by the efreeti queen, Hariqa, who has been trapped on the material plane by her bottle for millennia. While creating the weapon, Hariqa cursed it to gradually drive its master mad with its hunger for the heat of living creatures, and especially for fire elementals, in the expectation that Thiazadum would eventually be driven to find a way to enter the elemental plane of a fire, delivering her back to her home (As a safeguard for herself, Hariqa can banish Urfrost for 1 hour to a pocket dimension of endless cold as a bonus action). Each time Urfrost wins a conflict with the same wielder, there is a cumulative 5% chance that that wielder becomes permanently driven by the same instinctive hunger to feed Urfrost that it feels. Once this curse has taken hold of a creature, it can be broken only by death or a remove curse spell cast using a spell slot of 5th level or higher, which also breaks the weapon's attunement to the creature.

[Composer99]

Really cool (har!), evocative sword.

It seems fine to me for a sentient, legendary weapon.

As a wording nitpick, permafrost is soil, which I'm guessing isn't what the blade is permanently covered with.

You might say that it's permanently rimed with frost or hoarfrost instead?

[SilverStud]

Hey, I really like this! It doesn't seem unbalanced, and the flavor is neat.

Some things to consider:
Firstly, it seems likely to me that by the time players face off against someone with this sword, even a Natural 1 on the Con Save might not be enough to petrify them. Though, as I type this, that seems like a good thing. Oh well.

Secondly, you might consider reducing the speed decrease to 5 feet, but increasing that duration to 1 minute. It would be wicked awesome flavor + mechanics for it to slowly leech your strength until you're helpless.

OR MAYBE I'M JUST AN EVIL DM

[Inchoroi]

I think I'm going to steal this.

[Wryte]

Thanks for the feedback, guys! Glad you like it! :D

As a wording nitpick, permafrost is soil, which I'm guessing isn't what the blade is permanently covered with.

Y'know, I knew that once. :P Hoarfrost is indeed what I was actually picturing while writing the description. Changing!

Firstly, it seems likely to me that by the time players face off against someone with this sword, even a Natural 1 on the Con Save might not be enough to petrify them. Though, as I type this, that seems like a good thing. Oh well.

The group I'm running this campaign for consists of 3 rangers, 2 rogues, a druid, and a sorcerer, none of whom have higher than a 14 Con, so only the sorcerer actually has Con save proficiency, and a couple of them actually have negative Con scores. Yeah, DC 5 is still going to be failable for them. :P

Secondly, you might consider reducing the speed decrease to 5 feet, but increasing that duration to 1 minute. It would be wicked awesome flavor + mechanics for it to slowly leech your strength until you're helpless.

I'm drawing the saving throw effects from the Ice Devil's ice spear variant, where they are a 1 minute effect, and at first I was going to keep that, but then I realized that I really don't want to be making my players try to keep track of up to 3 different 1 minute duration effects simultaneously (by which I mean, I don't want to have to keep track of up to 3 different 1 minute duration effects per PC, because that's how it's probably going to work out XD).