Aether and fire shield are not broken. Both can be destroyed/stolen. Both can be bypassed: aether by a unit with momentum and fire by anything with immunity or growth (cards that gain 2 hp a turn aren't affected much by losing 1 hp a turn).
Currently, the only cards considered "broken" by the community are miracle and many of the rare weapon cards, especially owl eye. If any of you play long enough, you'll likely see why (miracle heals you back to (nearly) full life at a cost of all white quanta... which are only really useful for miracle in rainbow decks, and no one who is competitive plays a mono-white deck).
The game is still very new and is still being tested. It seems to have a rather laughable amount of bugs, still. We'll see how much work is put into the game; imo, it's already quite good.
And, Grain, you're beating some of the fake gods? Good job! Rainbow with time... you're probably using fate eggs, sundials, etc. I've never beat a fake god with that deck lol.
I'm currently running all darkness pillars with an earth mark. It sucks against the gods, but it's great in pvp.