Slithering tracker

A slithering tracker was a creature turned into an ooze in a ritual known to hags, liches, and priests that worshiped deities of vengeance.

Behavior
They were known to locate their victims by tasting the ground. They tried to kill their victims by draining their blood whilst suffocating them with their slime form. Once a slithering tracker killed a creature, their body became tinged with blood and left a visible trail of it for a certain unspecified time.

When a slithering tracker fulfilled their vengeance-seeking quest, they either expanded it towards other creatures or descended into madness, attacking without pause until it was slain.

Ecology
The ritual required the target to be willing and to be motivated by revenge. In the ritual, all the moisture from the target's body was drained, but their mind still lived on in it. Some considered this ritual a dubious origin for the slithering trackers, instead proposing the alternate theory that they were merely an advanced form of other oozes.