CR: Unknown but I'd estimate it around 4 or 5. Water breathing nearly trivializes this trap. See the last paragraph for two variants with slightly higher CRs.
Mechanical, Location Trigger, No Reset (self resetting due to the water elemental)
No save
60' deep well, 10' x 10' opening at the top, surrounded by a short 2' stone wall (think of a typical well wall)
Damage: SPECIAL, no physical damage from the well itself. See notes.
Search DC: SPECIAL. None, unless your players can somehow see a large water elemental motionless at the bottom of the well. Mine certainly didn't. I suppose detect magic or something that would magically enhance your detection of elementals would allow you to see it. If they can detect the elemental a DC 20 Search check would reveal the gist of how the trap works. Otherwise even the most thorough examination of the well would only reveal the treasure at the bottom and the adamantine manacles that are bolted to the stone floor.
Disable Device: SPECIAL. If the elemental is killed before the trap is sprung then the trap no longer functions. Once the trap has been sprung, a DC 30 Open Lock/Disable Device check will open the manacles, allowing the captured character to swim away (assuming that they are still conscious).
Market Price: Whatever the cost of the treasure/bait is plus the cost of the adamantine manacles (somewhere in the ballpark of 2000 - 4000 gold) and the construction cost of the well itself (unknown cost, estimated around 2000 gold). The enslaved water elemental will also need to be purchased or, if the creator is a wizard, "provided".
Notes:
This trap at first glance appears to be a rather innocuous well.
The horror!
If someone investigates the well or drops a light source in to it, they will easily see the treasure at the bottom. Their first clue that something is amiss is that the walls at the bottom of the well are covered in small but razor sharp protrusions (or very large fish hooks, for extra fun). Unknown to even those characters who swim to the bottom of the well there lurks a large water elemental, waiting for the opportune moment to attach the self locking adamantine manacles to the feet of the first character who manages to touch the treasure. From there the water elemental will move out of reach and observe the character. If they are a spellcaster, it will ready an action to attempt to disrupt any spell casting. If the character attempts to disable the locks it will ready an action to attack them during the attempt, disrupting it. If they appear to be attempting to pull apart the adamantine or are trying to pull it out of the floor it attempts to grapple them to prevent them from freeing themselves.
It keeps this up until they drown.
If someone attempts to help them or they appear to be immune to drowning, the water elemntal will attack the captive character until others get within range of its Vortex ability. It then uses it, teaching the characters just what those sharp protrusions are for (personally, I imagine that they would deal an extra 1d6 of slashing damage to creatures affected by the vortex ability). If there are hooks, well, that's really up to you to decide but I'd start with an extra 1d6+1 piercing damage and that the characters must make a DC 15+(the piercing damage that they just took) or be entangled (takes a –2 penalty on all attack rolls and a –4 penalty to Dexterity. An entangled character who attempts to cast a spell must make a Concentration check (DC 15 + the spell’s level) or lose the spell). A successful Strength check (at least a DC 15 but I'd recommend DC 15+(piercing damage dealt) allows the character to free themselves, forcing themselves free in this fashion deals another chunk of damage equal to the piercing damage they originally took. A successful Escape Artist check (DC again should be 15+piercing damage) would allow the character to get free without incurring further harm. Once entangled in this fashion a character cannot get entangled again or take any further damage from the hooks until they have freed themselves. If they free themselves into the Vortex again they should become entangled again. The sharp stone protrusions add 100 gp to the cost of the trap and 1 to the CR, the hooks add 500 gp to the cost and 2 to the CR. The hooks would also require upkeep to be performed regularly, they would only remain functional in dungeon that was being actively maintained.
I hope your players enjoy this one as much as mine did!
~ Skurilon
