And a bug i think. If i am dead, but i have cultivated to the end of the realm and unlocked the breakthrough option. I can open the breakthrough option, then just click on like the 100x speed button and the character might attack the boss. I can keep doing this until I finish the first boss. Then I can click finish and breakthrough, now I have more lifespan and am not "dead" anymore. This is particularly useful for QI gatherng and foundation level, since you can just power up for the full number of years, then after no lifespan you can enter this death challenge and continue.
if this behaviour was intentional, perhaps change make afunny flag for text replacement of "breakthrough" to "life and death isolation" or something silly like that.