Gallium, the Metal That Melts in Your Hand
The Gas Heavy Enough to Float Solid Objects
1. It's what's under your floating disk.
2. Take the 100' leap of faith down; the heavy air will cushion your fall, but then breathing becomes a problem as you climb the 10' ladder to the passage onward.
3. It makes your voice deeper, kind of an anti-helium. Kobolds huff this stuff and hide to make people run from the "loud, singing giant around the corner."
4. Floating skull! Run!
Hydrophobic (Water-Repelling) Surfaces
1. A necessary coating for underwater adventurers' spellbooks, bows, etc.
2. A corridor floor coated with this, then a trap dumps a blob of water, which races towards you like an Indiana Jones boulder. When blood spills on the floor, it beads and skitters like water on a hot griddle.
3. Invisible fishtank: foot-deep water on the floor surrounded by a hydrophobic zone. Will they figure out that this is the safe place to be when pursued by that water elemental?
3. Sprayed from the ceiling, is an encasement trap.
1. Clue, command word, true name, etc. written in cursive script as a twisted piece of wire that only needs an application of heat to snap back into the real letters
2. The same, but forms a key to a mechanical lock.
3. A strip of metal formed into an innocuous looking wristband expands and sharpens into an assassin's blade when placed in warm water.
4. A tangled wire ball placed in a piece of cold meat and fed to a mighty beast will, in its warm stomach, resume its former shape of a jagged, four-pointed cross.