Dying and/or resurrecting too often in Sekiro: Shadows Die Twice has a handful of negative consequences. One of which is the spread of Dragonrot.
When you are first told of Dragonrot, the maiden at the Dilapidated Temple will inform you that in order to seek a cure for the disease she needs blood samples from those affected by it. When someone in the world, or multiple people, are afflicted with Dragonrot, something called a ‘Rot Essence’ will appear in your ‘Key Items’ section of your inventory. This will give you a small idea, through clues, as to who is inflicted. For the first affliction, use the clues to locate that person and get a blood sample from them, and return it to the maiden at the temple. She’ll tell you that she needs some time to prepare a cure, but all you have to do is simply rest at a Sculptor Idol, and she’ll be all set.
Going forward through Sekiro: Shadows Die Twice, the curing of Dragonrot will not come so easily. Tracking down the materials you need no longer becomes a simple task of deciphering the clues given through the ‘Rot Essence’ item. For every other occurrence of Dragonrot in the game, you’ll need to find one ‘Dragon’s Blood Droplet’. Several merchants across Sekiro will sell these, and they aren’t terribly expensive, either. Once Dragonrot has started to spread again, simply locate a Dragon’s Blood Droplet and head to any Sculptor Idol you can find, or simply use the Homeward Idol to get there nice and quick. At the bottom of the list, you’ll see ‘Dragonrot Restoration’. Press that option, and you’ll be asked if you want to cure the Dragonrot. Select ‘Yes’ and all those affected with Dragonrot will be cured, while also giving you another great bonus.
For every piece of ‘Rot Essence’ you acquire, your Unseen Aid will drop. Unseen Aid determines the percentage chance you have of not losing your Sen and XP upon death. Well, luckily, curing those afflicted with Dragonrot also restores all your Unseen Aid! Unseen Aid will drop with every individual person infected with the disease, so pay attention to what’s happening in the world around you, and keep everyone as healthy as can be, because it helps you out, too!