2023 Advent Calendar Day 17: Ice Cube (spell)

The Incredibles (2004)

Ice Cube

1st level conjuration, 1 action, 30 feet, VS, Concentration up to 1 minute 

You trap one creature in a blast of icy mist. The target must make a Dexterity saving throw or become trapped in a block of ice. On a failed save, the target takes 2d6 cold damage and is restrained for the duration. While the target is restrained in this way, you can use a bonus action on subsequent turns to deal 1d6 cold damage to it automatically.

The mass of ice is an object with an AC equal to your spell save DC and 5 hit points, immunity to acid and cold damage, and vulnerability to fire and thunder damage. When the ice is destroyed, the spell ends.

At higher levels, its hit points increase by 5 for each slot level above 1st. (5hp/lvl)

This is probably the last spell I'll be posting for the advent calendar. I feel like I've done a lot of them, and they feel a bit low-effort. But this is a really fun one, and kind of what set me down the path of making all this wintery homebrew in the first place.

Freezing people solid in giant comical ice blocks is a cartoon staple. It's a great combination of debuff, action denial, and damage. It might be a little slapstick for some campaigns, but it really depends on the tone and narration - it would be a legitimately horrifying and deadly thing to experience in real life, and leaning harder into that can swing it in the other direction.

Mechanically, its restraining abilities compare to entangle, and its damage to burning hands, but is only single-target, which lets it split the difference and remain balanced. The ongoing damage can be seen as a bit of a fix for witch bolt, which I used in an actual game for the first time yesterday, and can confirm what everyone says - not a great spell. There are too many delicate circumstances that have to go exactly right to get more than a single turn of use out of it. Ice cube has far fewer restrictions - there's no range limit, and you can still use actions for other things. Of course, it compensates by being much lower guaranteed damage. Overall, I think it hits a nice median point between the three spells, while having an identity all its own.

Spells that create physical objects are rare and it's hard to estimate their impact. Most others are summoning monsters to fight for you, but ice cube doesn't explode the action economy the same way. There are some higher-level conjurations like magnificent mansion, but those all seem to be indestructible creations of magical force. Offhand, the only one I can think of that conjures a destructible object with armor class and hit points is wall of stone, so I'm flying blind trying to balance it. I have another homebrew spell, igloo, which is basically tiny hut but 2nd-level and destructible, that has 15 HP per level, but it's meant to be tougher and last through the night. And there's not a lot of guidance anywhere else in the system either; as much as I appreciate that one page in the DMG, destructible environments are clearly an afterthought. Overall, I figure one good hit ought to do it, at its lowest level.