What happens if I lose all three hearts?

Simple question—not sure if I missed it somewhere in the tutorial. I know I can buy hearts back but what happens if I lose all three? Get booted from the level and have to buy at least one back before continuing? Or do they come back automatically? Or do I lose progress? Don't want to find out the hard way.

Solution 1:

If you die in a level, you will be sent back to the Tavern with 1 heart. You will not lose progress.

You will lose any materials collected during the last level and limited use equipment will stay used, but otherwise there is no punishment for dying. Challenge progress is kept after death. You can simply heal up at the Tavern and try the level again.