I applaud you for making a decent monster. So many of the ones on D&D Beyond are rubbish that looks like it was written by a 4th grader. However, there are a couple of oversights.
The resurrection thing means you have to fight him 10 times and do a total of 3000 damage, which is hypothetically possible for minmaxed builds (I found a party composition that can do thousands of damage in a round), but not fun.
Spellcasting is off. He knows way to few spells and is missing 2nd, 7th, 8th, and 9th level slots, as well as cantrips.
Frost touch is just not worth using when it does barely more than a quarter of the damage of the ranged attack.
Freezing Strike is nigh=guaranteed to remove a character from the fight, with no counter or repeat saves.
This guy is clearly a boss, but has no LR or legendary actions.
The Con save expertise is calculated wrong, and plain unfun.
The Snow lair action is really poorly designed. Yay, you can't do anything! How fun! It also doesn't need to be so many sentences.
As for the Ice Arcanum, it is very boring. Legendary items should be epic. Not dieing is not epic.
On to the Staff of the Frost King.
Did you really think summoning an adult dragon at will is balanced?
This new version is much better, although the reset to 280 health should only be once a day, and damage needs to be slightly lowered to account for legendary actions. The boss dropping to one knee but staggering back to his feet after his magic staff emitted a surge of revitalizing energy once is awesome, but if you do it a second time, the players are going to get concerned about the length of the fight, and it won't be as dramatic.
To make the Staff of the Frost King more in line with other items, you might want to make it regain a random number of charges, rather than all of them. And how long does the regeneration last?
For the Ice Arcanum, just make it 10 charges, because you can't have more than +10 in an ability score.
I created some Frost themed Homebrew.
Frost King (Monster): https://www.dndbeyond.com/monsters/6080310-frost-king
Ice Arcanum (Magic Item): https://www.dndbeyond.com/magic-items/11079903-ice-arcanum
Staff of the Frost King (Artifact): https://www.dndbeyond.com/magic-items/10987869-staff-of-the-frost-king
I would like some Feedback
I applaud you for making a decent monster. So many of the ones on D&D Beyond are rubbish that looks like it was written by a 4th grader. However, there are a couple of oversights.
As for the Ice Arcanum, it is very boring. Legendary items should be epic. Not dieing is not epic.
On to the Staff of the Frost King.
Did you really think summoning an adult dragon at will is balanced?
Thanks. I tried to fix the issues with the Frost King here:
https://www.dndbeyond.com/monsters/6115137-frost-king
It still does’t have Level 8 and 9 spells because iam not sure what would fit.
On the other ones i am still working on.
This new version is much better, although the reset to 280 health should only be once a day, and damage needs to be slightly lowered to account for legendary actions. The boss dropping to one knee but staggering back to his feet after his magic staff emitted a surge of revitalizing energy once is awesome, but if you do it a second time, the players are going to get concerned about the length of the fight, and it won't be as dramatic.
Misty Step is great for a boss to have.
I updated the Ice Arcanum:
https://www.dndbeyond.com/magic-items/11083683-ice-arcanum
The Staff of the Frost King is changed too, i made the summoning more expensiv and at a Long Rest i only regains half of the total charges.
https://www.dndbeyond.com/magic-items/11083743-staff-of-the-frost-king
An only a littel change to the Frost King ( The Soul of Ice Trait can only used once but he got some more Total Hit Points and the damage is lower).
https://www.dndbeyond.com/monsters/6116917-frost-king
To make the Staff of the Frost King more in line with other items, you might want to make it regain a random number of charges, rather than all of them. And how long does the regeneration last?
For the Ice Arcanum, just make it 10 charges, because you can't have more than +10 in an ability score.
the Ice Arcanum has 10 charges now:
https://www.dndbeyond.com/magic-items/11083683-ice-arcanum
The Staff of the Frost King:
https://www.dndbeyond.com/magic-items/11087961-staff-of-the-frost-king