# Falling after being Knocked Prone on a Slope

I'm setting up a trap for my players.

They will be entering a tunnel with a rather steep section - steep enough to require climb checks to avoid falling but not so steep it can't be counted as "ground".

Perhaps like 60º-70º?

My BBEG (Druid/Wizard) will have trapped this slope using two Glyphs of Warding. He stores Grease on one, and buries it using Mold Earth more than 1 foot deep in the stone. He then stores Spike Growth on the other (burying it as well).

When the PCs come within 5ft of the Spike Growth, it will trigger. The Grease will trigger one round after the Spike Growth, hopefully knocking the PCs prone.

I know that Flying creatures being knocked prone fall. I imagine that someone being knocked prone on a 60º incline would also fall, but might have a chance to catch themselves.

My question is how do I rule being knocked prone while on a steep floor?

My options I'm considering are:

1. The PCs fall until something physically stops them (like falling if flying)
2. The PCs get a chance to grab onto a surface each 5' of movement they fall.
3. The PCs get a chance to grab onto a surface once/round they fall. Each $$\X\$$ they succeed the check by translates to $$\(X + 1) \times 5\$$ feet less they fall.

Of course, each 5' they move over the steep floor covered by Spike Growth, they'll take 2d4 piercing damage. #evil_dm_laugh

As an aside, my PCs have already encountered several Glyphs of Warding, so this won't come as a huge surprise for them.

• This can definitely be answered by reference to published adventures, or from personal experience. – Mark Wells Oct 26 '19 at 0:00