I ended up 6 for 7 on each Ragnarok (no Elixirs used). Lost my first Medusa today due to Petrify spam, eventually ending with Mordred getting Petrified with Maiden's Prayer ready. I also had a number of close calls on both fights where I ended with fewer than 5 alive.

These Ragnaroks were pretty hardcore, so I feel pretty confident about the lasting power of my Water team, even with only 1 Water SSR (Shiva). From here on I'll likely be focusing on my Wind team, though I'm still waffling over whether to pick up Titania or Cthulhu with my first Miracle Ticket.