Could you post a screenshot of that skill "aquactic creature skill aquactic sing", I actually don't know which your are talking about.
Viewing post in Feedback (Early Access Version)
Yeah i added some hint in the battle and also added a recommend level of 15 to the warning before battle.
And I changed that the skill automatically gets added on easy and normal difficulties when entering that boss fight.
So that should make it less confusing.
Oh i see, when i will look at that skill and fix it!