Celestial Rebirth
Celestials don't die, but they do rebirth. When a Celestial has used up all of its energy, it will go in a deep meditating state at the core of Deep Space to disintegrate into life particles that build back into a new Celestial over a long time. However Celestials can be killed when attacked in their deep meditating state.
Is going to be part of a giveaway.