aaaa sorry for not doing these in order, i just got ideas for these two so i decided to throw em in here and prove my existence
in the night or similar levels of darkness, you are able to turn your arms into large bat-like wings. the wingspan can be manipulated by you but cannot grow longer than 371 centimeters. there is no time limit, though they get weaker with any light stronger than moonlight or starlight, eventually fading away either with exposure to enough bright light or prolonged exposure to dim light. possibly avoidable with the use of covers over top of the wings, as they are solid, though the extra weight would at least somewhat negate the purpose of having them.
you are able to turn parts of your body into a fizzing, bubbling substance that keeps itself more or less in a form the shape of said body part, the specifics of which can be changed to your will from a harmless substance to a highly corrosive acid, and regardless it will not injure you, though different solutions will require different resources from your body. however, you can only do this for 5 minutes, and after every period of using this ability you have to cool down for an equivalent period of time before using it again for any other part of your body.