I summon Oobleck Kahn in Attack Mode!

[SangoProduction]

I can conjure somewhere around 1250 cubic feet of water in a single action. And then as a Quickened action, I can conjure a little more than 3,125 lbs of plant matter.

I want to weaponize this ability in the most creative way possible (aka, a way that logically follows, not simply one presented in the rules).

Anyway, corn starch has a density of 33.78 lbs / cubic foot. Which means we can conjure right around 93 cubic feet of corn starch. A typical oobleck mixture calls for 1/2 the volume of corn starch to water, so really, I can only make use of 185 cubic feet of water for around 277 total cubic feet of coverage.

Or right around 2 full 5-foot cubes of oobleck - so maybe total coverage in one square and rough terrain in adjacent ones? But what would the properties of such a block of oobleck be? How long could it even potentially trap someone? Would it be a swim check to get out, or do they straight just need to move slowly to make sure it keeps flowing around?

But that's the idea I had. Does anyone have something more creative?

[Calthropstu]

Rules expressly forbid what you are trying to do. But there IS a loophole.

Create a massive container and have someone with enough strength to carry what you are creating. Have him airwalk upwards. Cast your spells and he dumps it on his turn.

The result is not covered in the rules. So gm interpretation.

[LunaticChaos]

Just physics wise this is unlikely to work because oobleck must be evenly mixed and just having two materials in a similar space doesn't necessarily do that, let alone rules mechanic problems.

But making the assumption it does work. Oobleck is only highly resistant to impacts, its not that much more viscous than water. It will quickly spread out if left freestanding. So it might act as a relatively hard wall for a single round, then it will quickly spread out and likely form difficult terrain. As a DM (Assuming I ALLOWED it to actually work) I'd say it would create a wall for one round per block of height, and it would drop by 50% per round, providing half cover then no cover for any block its not fully occupying the height of. With its area covered increasing by a 50% per round as well. Probably not FULLY in line with laws of physics or mathmatically sound, but quick and dirty answer for gameplay purposes.