My bad... All this time I thought he was Polish, but he is from Indonesia. Too similar flags...
Similar in an upside-down world, you mean. And yes, pun intended.
On-topic:
Aether seems fitting, time too. I like Entropy. But Death and Gravity feels too off thematically. While i know it's mainly the design, you should maybe try a more "thematic" approach. I can't feel Death's decay or Gravity's order, for example. Different from Aether (semi chaotic particle), Entropy (self-explanatory), or Time (has this "time flows" feeling).
Life's good, it feels full of energy and... root. Yeah. Greeny swirly vital DNA, or whatever. Nice.
Try Darkness, and maybe try making it based on a spilled Liquid Shadow. Black dust/ink/particle swirling seems good and is thematic.