Trap Showcase: Feller’s Fall

My campaign setting, which I’ve been running games in for over a decade now, has a unique alchemic item that I call Feller’s Fall. Originally, it was a goofy unique trap for an alchemist’s laboratory, but even when my players triggered the trap they loved it so much that they asked me to let them make it too! (See the item description below for use in your games.)

The quick and dirty is that Feller's Fall is basically neon green goo that’s highly flammable, which when touched reverses momentum and doubles it. What this means in practice is that a creature entering the green goo gets flung in the opposite direction like they were launched out of a sling shot. Combine this with an obvious and easy thing to avoid: spikes on the walls, pits on the edge of the room, or (my personal favorite) explosive runes. Now the trap is set: don’t touch the bad thing, who would even do that anyway? Then Feller’s Fall flows from the ceiling, rushing the players through the room unless they contend with the possibility of being forced into whatever bad thing you set up. It’s a fast execution trap which gets players thinking and sweating over how to deal with it once you say it’s happening, especially when they know what it is. Don’t forget it’s flammable, this can be a quick trick that catches a party off-guard if they’re all using torches exposed to the goo that’s washing them away (feel free to stack up the damage if a wave of Feller’s Fall is burning and not just one flask).

Feller’s Fall (Item Description)

Effect: A single flask of Feller’s Fall can cover a 5ft square, treat targeting a creature with a flask as a ranged touch attack with a range increment of 10ft. When a creature is coated in Feller’s Fall or attempts to cross a square coated in it, they must make a Balance check DC equal to 10 + [(Speed Used to get to the square / Movement Speed) / movementspeed/5] or be flung in the opposite direction in which they were moving at twice the rate they entered the square. Feller’s Fall is also highly flammable and when ignited burns brightly for one round, dealing 3d6 points of fire damage to any creature or surface touching it. When the round is over, the Feller’s Fall is gone, leaving nothing but a bright green scorch stain on the surfaces it touched.

Cost: 50gp per flask
Crafting DC: 35 Alchemy Check

Examples

Creature A:
Speed: 30 ft
Moved 5 ft before entering square
DC = 10 + [(5 ÷ 30) × (30 ÷ 5)] = 10 + (0.166 × 6) = 10 + 1 ≈ DC 11

Creature B:
Speed: 60 ft
Moved 60 ft before entering square
DC = 10 + [(60 ÷ 60) × (60 ÷ 5)] = 10 + (1 × 12) = DC 22

Creature C:
Speed: 20 ft
Moved 10 ft before entering square
DC = 10 + [(10 ÷ 20) × (20 ÷ 5)] = 10 + (0.5 × 4) = 10 + 2 = DC 12