So if Helios loses, are we out?
No you wouldn't be out. You currently can salvage 14
cards from your 3 losses so if Helios' deck is 31 and he lost you would be able to salvage one more
card to make a legal deck. Also i'm sure you have a
card or two in your vault still along with a bunch of other cards.
Anyhow you'll find out tomorrow morning 11am PST to see if he wins or loses.
ETA - although if they use purify that would mean they would have to splash water which really would slow whatever deck they are going to use (i'm guessing momentum since they know we have dim shields and bonewalls). So they probably won't use purify.