Because I'm very confused...Anyone have any tips or tricks for me?

Try to bost your stats with better equipement or more adapted one.
That keep the mend for this battle as it have 25 turn cool down and get your pets mana max out so you can use the finishing blow quicker.
Your water element must be first in your party to take most of the hits.
Maby get some healing item from the mission could help as well.