Vanish & Vanishga

Okay first, don't use them. They suck, and they don't work at all. Vanish makes one person turn invisible, while Vanishga makes the party turn invisible. At least, that's what they fail to do. Enemies can still see you, and will still attack you, so don't use them. All you do, is cast the spell upon yourself.

That's good, the Tournesol is really strong.

The spells Vanish and Vanishaga are supposed to make your characters invisible but enemies are still able to see you. They are pretty much useless. The only reason to get those two spells are so you can get the crystal in the sky pirates den by getting all the magicks.

If you cast it on Reaper enemies they will ignore you as long as your health is above 50%

Its really simple, others think they are used for going undetected by monsters. regular enemies will always notice you. Try casting float and vanish to see if it is your footsteps that make monsters notice you. If that doesn't work, than i know what your problem is. these spells are used with Construct type monsters. The constructs are like robots, so they can't see organic (human) things. Check your bestiary or online to see what monsters are constructs. There are a lot of them out there. Good luck.