Celestia, the card you didn’t know you needed, if you’re playing Sophie (13-119L). Why? Well we’re glad you asked, but first …
On to the card
4CP : Water/Ice
Forward
Job : Warrior
Category : Type-0
Legend
9000 Power
“The Water Characters you control cannot be broken by opposing Summons or abilities that don’t deal damage.
When an Ice Character you control is chosen by your opponent’s Summons or abilities, choose up to 1 Character. Dull it and Freeze it.”
That first ability is all you need, as Sophie is Earth/Water she counts as Water. (Correct me if I am wrong.) With her not being able to be broken by abilities or Summons that don’t deal damage, she will most likely not be able to be broken if you have enough Earth and Water Forwards on the field. It is simple as that.
Now, how will you pay for Celestia without having to make a tremendous change to your deck? Very Simple. Tyro (11-072R). With Tyro, you can dull him for 1CP of any color. I’ll 
keep saying it, too. Great card, if you play Earth you can splash any other color you’d like as you’ll have a way to pay for it.
That was my take. And, then I took a look at FFdecks.com Ashe’s Prison was the deck.
https://ffdecks.com/deck/5358425582075904
And, saw something I did not think of. I never said I knew everything. But, apparently you can pair Celestia with Minwu. Your Water Forwards will be unbeatable. And that deck looks like it would be fun to play.
Let us know what you think in the comments.
