This spirit appears and smells similar to a bloated, decomposing body except you can see through it.
Speed fly 30 ft. (perfect)
Creatures that take damage from the riverswell spirit’s chilling touch begin to have their lungs fill with water from the spirit’s drowning touch. If the creature is not already making Constitution checks to keep from drowning, the creature must succeed a DC 10 Constitution check. If the creature made a Constitution check in the previous round to keep from drowning (either from following the drowning rules or from previous drowning touch attacks), increase the DC by 1. This DC is in addition to the standard DC increase gained every round from the drowning rules and is cumulative with each successive drowning touch attack. The Constitution checks continue until the creature takes a full round action to spit up all the water accumulating in their lungs and breathes air, receives a DC 15 Heal check from another creature as a standard action to force the water out of their lungs, is the target of a remove curse or similar spell, sustains any amount of fire damage, or fails the Constitution check. Creatures that fail the Constitution check begin to drown as per the normal drowning rules. Creatures that do not need to breathe or can breathe water ignore drowning touch.
A riverswell spirit cannot be killed by destroying the spirit. Instead the physical body to which the riverswell spirit is tied must be destroyed or blessed. If the hit points of the spirit are reduced to 0, it rises again the following time the river floods and hunts for a new victim. A riverswell spirit cannot travel more than 400 ft. from its physical body.