Health Tonics are special potions Plague Knight can drink in Plague of Shadows. Each health tonic increases Plague Knight's maximum hit points by two up to a limit of twenty hit points total and refills his health by two hit points. If Plague Knight's health is already at maximum capacity then health tonics will still heal him two hit points. On death all increased health capacity from Tonics is lost which makes Pits and Spikes very dangerous hazards for Plague Knight.
Health Tonics can be found in Dig Piles, Fishing Spots, Platters and the large chests relics are usually found in. In addition Plague Knight can refill his entire Tonic pile from the Magicist at 100 gold per tonic. If Baz was recruited he will allow the player to refill for free with tonics he stole from the Magicist.
- There is usually a chest with food and Health Tonics before each boss. With this in mind, should the player perish against the boss and lose all tonics, it is possible to refill some of them before starting the boss. Strategically, the player can purposely die on the boss to respawn, re obtain tonics and repeat until they're maxed; that way the player can start a boss fight with maximum health. However, this will only work if the player does not drink the tonics whilst trying to max them. This trick is not work in New Game Plus.