I have to think that singing the Mana song in battle is not worth it.
Figuring that you can twist three songs for the price of one Mana Song,
and that the Mana Song buys you an additional one-third of a spell for
each caster, the breakeven point should be at nine or more casters in
your party, which means never. And that assumes that they are all OOM.

If I have to pick one song to sing, it's probably Lullaby (which
impressed the heck out of a bunch of level 42-50s in Lower Guk the other
night - I was level 34 at the time). I sing the Mana Song when we're
done.

Kenross Cantoforjado, 34 songs, Innoruuk