Of Water & Stone
Type magical; Perception DC 22; Disable Device DC 25 (or 15 with a DC 20 Spellcraft check)
Trigger location; Reset none
Effect When triggered, a massive whip-like vortex of water spanning up to 60 ft. in length erupts from the cascading face of the nearby waterfall reaching all the way to the inscribed rune.
The maelstrom force of the vortex dredges up stones and silt from the waterfall’s source, creating a cyclone of jagged debris within the watery tendril.
The vortex lasts for 3 rounds once triggered. Any creature within 30 ft. of the twisting watery vortex must make a DC 18 Reflex saving throw each round until it dissipates to avoid becoming drenched and pelted by debris (2d4+1 bludgeoning damage).
On a failure, the creature begins to be forcefully drowned by the vortex of water.
After the third round the vortex simply vanishes, causing a rain of stones and debris to fall through the air from its previous path. Any creature that was within 30 ft. of the vortex takes 1d6 points of damage from falling debris (DC 15 Reflex for half damage).
If noticed, an of water & stone trap appears as a crudely etched sigil on a rock or upon the ground. A DC 20 Knowledge (planes) check reveals that the sigil is actually a crude elemental symbol for water encircled within a stylized elemental symbol for stone.