the mana potion is for if you somehow mess up and require mana/energy to complete the jobs. its a fail safe.
Glad you liked it.
also this may be the only time i mention it, but the game is not 'anti-sex' the mc comes from a different culture background and is having culture shock from the polyponies she is interacting with, if there was more time 'and after voting I'll be allowed to do an update' Wonder will have a moment where she will start to build toward her own harem having found she now likes this new way of love making she had never previously considered. (the theme of the game could be said to be idealism vs reality and learning to accept new truths as you grow up. or something like that)
This story is more of an 'act one' and I ran out of time so i couldn't put in an act two (otherwise we'd have derpy in here somewhere)