Piercer (CR varies)

Piercer (Hazard, Aberration) CR 1/4+

XP varies
Hazard, Aberration

Piercers resemble 1-foot-long stalactites and are found underground in caves and caverns hanging from the ceiling waiting for living creatures to pass underneath. Those viewing a piercer must make a DC 20 Perception check to discern its true nature; else it is overlooked and mistaken for a normal stalactite. Piercers gather in clusters of up to 20 creatures.

When a living creature stands in a square directly below a piercer, it drops and attempts to impale the unsuspecting foe. The creature can make a DC 15 Reflex save to avoid the piercer’s attack. If the save fails, the target sustains 1d6 points of piercing damage. If the save succeeds, the piercer misses its target and may not attack again until it climbs back
into position (moving at a speed of 5 feet per round). A piercer on the ground is easily dispatched, though touching or attacking it unarmed or with natural weapons causes it to secret an acid that deals 1d4 points of acid damage to the opponent each time one of its attacks.

Piercers can grow to tremendous lengths. Those of 2 to 4 feet in length are CR 1 and deal 2d6 points of damage if they hit a foe (1d6 points of acid damage if hit). Those reaching 5 to 6 feet in length are CR 2 and deal 3d6 points of damage if they hit. Their acid deals 1d6 points of acid damage. The DC to avoid a piercer’s attack is 15, regardless of its size.