Ball of Tar (5e Equipment)
From D&D Wiki
This stout glass vessel contains a roughly spherical lump of tar. When you drink the potion, you begin sweating out tar, which covers your weapons and equipment. You leave a trail of tar behind you, turning any space you move through into difficult terrain.
When you make a successful melee attack on a target, the tar sticks to the wound and quickly spreads across the targets' entire body. They become restrained, although their movement speed is only reduced by half, and leave behind an obvious trail of tar. Survival and Perception checks made to locate the target gain advantage, and they make Stealth checks with disadvantage.
This potion lasts for 1 hour, after which any tar produced dissolves into oily black smoke.