This section of Sekiro: Shadows Die Twice guide includes the description of the Flame Vent, which is one of the prosthetic tools available in the game. Below, you will learn how to unlock the Flame Vent and how to use it.
How to unlock the Flame Vent?
You can unlock the Flame Vent relatively early, but first, you have to unlock the Access to Hirata Estate. More information on that can be found in the How to unlock the Hirata Estate? section of this guide.
Continue exploring the Hirata Estate until you reach the Estate Path sculptor's idol. Investigate the side area with shacks and some enemies accompanied by the wolves.
You have to reach the campfire shown in the screenshot and retrieve the Flame Barrel (required to craft a prosthetic tool) from it.
Return to the Dilapidated Temple, and talk to the Sculptor again. Select the option to craft new gear and choose the Flame Vent. The toll will be crafter without any additional fee.
Place the newly crafted Flame Vent into one of the three slots for the prosthetic tools. During the game, you can switch between the active gadgets (by pressing the triangle / Y).
Utilization of the Flame Vent
Flame Vent deals fire damage and sets enemies on fire with short range fire projectiles. Theoretically, you can use this tool to eliminate any opponents - however, it is not worth to waste it on weaker enemies.
The perfect use of Flame Vent involves attacking enemies who are afraid of fire - mainly four-legged creatures encountered throughout the game. One of such monsters is the Chained Ogre from Ashina Outskirts. Attacked four-legged creature ceases its attacks allowing you to weaken it with everything you've got.
Using Flame Vent is not unlimited - each attack uses 3 Spirit Emblems. Save this tool for monsters and more powerful enemies.