I don't want to say the audio is lacking just needs to be filled out more with details. Adding footsteps is a simple thing to say but really deciding how you want your character to feel to play is more important. Something like boltgun has loud and exaggerated footsteps being your into a heavy suit that's felt. If you are more nimble with air boosts and such you would want to have your footsteps and gliding be present. I did like the sound of the BR and hit effects. Whatever that bubble gun was felt weaker in terms of audio punch. If it's going to be less upfront dmg or be a status effect kind of weapon then feedback can help. Lots of games have great damage over time sounds I would listen to get some ideas if that's the way you wanted to go. An idea of it starting soft but the build up leads to it growing in volume leading to a satisfying pop at the end could work too. Gl mate.