What is Deathroot used for in Elden Ring?

sportskeeda.com:

There are plenty of items in Elden Ring for players to make use of, including the Deathroot drops that they'll find around the world. As players progress through certain boss encounters in the game, they may notice that Deathroot is one of the rarer drops in the game.

Not every boss in the game will drop the roots either. Typically, they can only be found in optional dungeon encounters that are scattered around the map. Some dungeons will drop items like Ash summons, but others will have the coveted root rewards.

Most of the time, Elden Ring players will be able to find Deathroot from undead bosses in catacombs or in the open world. They can even be found as rewards as early as Limgrave, but they are not given an easy explanation.

Overall, they are a currency that can be traded for some unique rewards. But players must first find the location of the Beast Clergyman in the East.

Where to spend Deathroot:

Each subsequent root that players give to the clergyman will net them a better reward related to the bestial sanctum. This can include Ashes of War and materials.

The boss that players should be looking for is the Tibia Mariner, which appears in three locations around the map, including Limgrave. These boat-based bosses with skeletons can typically be found in ruins that have lakes within them.

Then there is the black knife assassin boss, which is also in Limgrave, near the yelling warrior jar named Alexander. This dungeon boss will drop a root as well as the talisman for health in critical hits.

With all of these together, players can easily collect the roots that they need for new rewards within Elden Ring.