In Rime of the Frostmaiden there is a new Wizard spell. Frost Fingers.
Casting Time: 1 action
Range: Self (15-foot cone)
Components: V, S
Freezing cold blasts from your fingertips in a 15-foot cone. Each creature in that area must make a Constitution saving throw, taking 2d8 cold damage on a failed save, or half as much damage on a successful one.
The cold freezes nonmagical liquids in the area that aren't being worn or carried.
At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d8 for each slot level above 1st.
A 15 foot cone of water, frozen solid. If you're underwater and a medium creature is inside a 15 foot cone of ice they're probably dead. So if a target saves vs the spell, but is still in the wrong place at the wrong time, they're dead... or perhaps just drowning? Depends on the DM I guess. Technically maybe an underwater creature counts as "wearing" the water in its 5 foot cube, but even then, they could be trapped in the water within the ice and out of combat.
Obviously, just as a regular spell, it's not a bad one... but if your foe is knee deep in water or underwater it's a great one. Hell, if it's raining you could argue for some bonus bludgeoning/piercing damage from instant hail.
The spell freezes all liquids... so acid, lava, beer, wine, whatever.