Here's what I'd do, just use melee for the wizard, and spellcasters/archers supporting the horseman and the warrior. Because the wizard has range, and all she needs is protection up front, and since the other two are melee, they need all the range possible. + if this helped at all.
Play Swords & Potions. Play another game for ten minutes until I can play another day on S&P. Play 1 day, switch back to my other game after 2 minutes....starting to get PISSED OFF.
@leedennig: I don't think it's Mozilla that caused you to lose your save file. Remember, this game is still in beta mode, so expect to lose your save file.
Keep in mind that after you beat a wave, your hunger, air, and total health supply is replenished. Also, if you're low on hp, decrease your size, and up your diving and hunger (as napolj2 stated). Plus, try to eat some aliens. I've seen my whale restoring 300 hp after eating one.