After each win, the team can salvage cards from the opponent. Winning team picks 6 cards from the deck posted by the losing player, which will be added to their Vault. These cards become part of the Vault and can be later used by anyone on that team. Salvaged cards are always unupped even if the original card is upped. Maximum card amount of 18 doesn't apply to salvaged cards.
When you salvage cards, you are not really taking cards from the opponent, you are merely taking a copy of that card and putting it into your Vault. In Elements terms, you are using Parallel Universe on those cards.
The previous is good to keep in mind.
Salvaging/Discarding ideas:
As
Fire we should probably be discarding
Pillars, having the ability to convert 12 cards into pillars per turn and having Immolation | Cremation as great assistance.Against

Aether we might consider taking their
Dimensional Shield | Phase Shield, more defense for us, as we bolt them.Against

Air let's consider taking possibly
Flying Weapon. These cards are very flexible and provide us with a staple deck and even a forum member, Flying Farenheit.Against

Darkness, I get the feeling that the
Devourer | Pest will be all over the place, since they won't be able to convert cards into them but serve as pillars anyways. We should also be looking into their duality and splashing them with Immolations and Lava Golems with Mark of Earth might be interesting.Against

Death, having more copies of
Arsenic will help us in those rainbow decks that Fire can make so easily, and maybe even more Poison for us so that we can make duplicate PoisonBolt decks.Against

Earth the card to look at is
Enchant Artifact | Protect Artifact. Everyone will be worrying about 2 main things to create a deck, Creature Control and Permanent Control. With this card, our Fire Shields would mean a lot more pain.Against

Entropy, the obvious card to salvage is of course the
Nova | Supernova following the same "can't convert to it" logic. These are seen in a lot of Firebows and just relying in Immolations leave any Firebow in a tricky spot without any Photons.Against

Gravity
Momentum | Unstoppable is one of their cards that really shines. Fire creature know they can be brittle at times, and a Crimson Dragon with 4 health fears no longer bolts or rains of fire. Shields can mess us up a lot of the times, and to be able to go right through them will come to Fire as a major advantage.Against

Life, perhaps having their
Heal | Improved Heal would help as jmdt's Christmas for your score deck has shown previously.Against

Light, more Photons for our Immolations would work nicely, and if Darkness or Death are doing well, we might want to take more Holy Lights. Though adding more Miracles to our vault will help us as well.Against

Time, it's been said before that
Reverse Time | Rewind is one of their cards to fear, especially with our growing creatures and Immolations. So why not use them for us? Another viable option are those Precognitions that everyone seems to value for their deck thinning.Against

Water, we should be looking at Death's progress in case we need to take more Purify from Water or not, but that's more situational. In a more typical case,
Steam Machine would work nicely with Fire.[/list]
These are just my opinions however, please feel free to post your own.