Healing

Outside battle, healing flasks are the only way to recover. Open Gear, buy a flask on the Supplies tab, then tap Drink.

Each book hides a trader who sells the same flasks for less. Ask them for their wares and the drawer opens at their price. You never have to find one, but it saves gold.

Going up a level also restores you to full health.

Losing a battle

Losing a battle, or surrendering one, leaves you with low health and takes a share of your gold. How much depends on the difficulty. Nothing else is lost: you keep your gear, your level and your place in the story.