D&D 5E Need help with an 'environmental hazards' idea

[Dr.Gonzo]

So i'm making a boss room in the basement of a gang hideout. The room is basically a drug lab used by a slum gang to refine crystals smuggled up from the under-dark into a drug that they sell.
There are tables covered in alchemy equipment, and big glass bottles and stuff, and I also wanted to include a variety of barrels next to the different tables. Some with flammable stuff that explode, some with weird alchemy chemicals that explode into clouds of poison smoke AOE, and I also wanted some frost-barrels that do cold damage.
It's the "frost barrels" that I need some help with. So far i'm thinking they cover an area of floor in slick ice that is difficult terrain, and might make people slip, also I was thinking anyone nearby when it explodes might get launched. But I don't know what would set it off. would an arrow make a barrel of alchemy-liquid-nitrogen stuff explode? would a fireball set off a barrel of alchemy-liquid-nitrogen? Maybe i'm thinking about it too much...

 

[Tony Vargas]

I suppose anything that breached one could do it, that'd be damage. You might want to restrict it to slashing or bludgeoning damage, or other damage types that'd be similar, like thunder. Or you might have them go off if they're moved.

 

[Dragongrief]

How "realistic" do you want to go?

Cold things are less likely to be explosive - that's more of a heat/fire thing. If you want to go for a liquid nitrogen feel, breaking the barrel would result in a pool of difficult terrain with cold damage and the chance to be frozen to the ground if you end your turn in it (Restrained condition), with a Strength check required to break free.

 

[Paraxis]

Pressurized Cold Barrel

• A square with this barrel in it is considered difficult terrain.
• A creature sharing a square with the barrel gains half cover +2 to AC.
• An attack that rolls a natural 1 against a creature in the square or adjacent to it hits the barrel.
• An attack that misses a creature do to the cover the barrel provides hits the barrel.
• The barrel has an AC of 10 and 10 hit points.
• The barrel takes damage from any AoE spells or effects it is caught in including other barrels.

If the barrel is reduced to 0 h.p it explodes in a 10' radius doing 5 (2d4) slashing damage and 5 (2d4) force damage.
Any creatures in the area are also pushed 5' away from the barrel and knocked prone.
Dexterity save DC 12 takes only half damage and no push or prone.
The explosion creates a zone of cold and ice, any creature that starts its turn in an area 10' radius of the former barrel takes 5(2d4) cold damage and speed is reduced by 10' for the remainder of it's turn.
The zone lasts 1 minute.

 

[Riley37]

There's a scene in "Terminator 2" which might give you inspirational imagery.

 

[Dr.Gonzo]

Aha! perfect. Thanks man; this is pretty much what I had in mind. I might change the speed reduction to difficult terrain with an acrobatics save to avoid slipping.