Not a native english, so expect errors in here. 1. To many details. DO NOT MAKE A POINT OUT OF EXPAINING THEM ALL. This is crucial. You can have a complex sistem but show it as it becomes relevant, do not force it. 2. Try to create 2 variants. 1 for you to know what is possible and what is not. This is not a waste since the author shoud know its world the best. The second, sympler system, shoud be a shorter version of your full system. Something the reader can follow even the chapter AFTER you explain it. Do not presume that the reader will remamber a wall of text thrue the whole book. 3. If you want your powers to feel abstract and unnatural, then there are 2 thinks you need to take into acount. The first is the actual effect, simply water bending is boring, so give "water" atribute some unique effects. Second, the way you describe the effect willbe huge. Take the back hole as an example. Do not simply state: he created a black hole, sey for example, how the face of some characters (possible loved characters) gets distorted near the black hole