If you die while playing through a world, quest or event, you will be given the chance to resurrect yourself!
As soon as you die, you'll be prompted with a resurrection option. For the cost of one revive coin, your hero will be healed and you can attempt to complete the run.
Revive coins can be used to resurrect yourself once during a run, but you have three chances to resurrect. The other two times you will need to spend gems to resurrect yourself.
Revive coins can be purchased through special offers, or as rewards from gameplay.