"Salvaged cards may be transmuted at a two to one (2:1) ratio into any in-element card which you do not already have 12 copies of in your Vault, except for Shards."
I do not understand this rule, why are Shards excluded?
In my opinion, the fairest way to handle transmutation is to let the point total of the cards transmuted be larger than or equal to the card you want to transmute towards. So Fractal -> Fire Bolt is OK, but Skeleton -> Fire Bolt is not. The ratio would then be determined by the number of cards needed to add up to the price of the card you want to transmute towards.
Shard transmutation ban has been removed - this was a rule from last War that we didn't catch, I see no reason for it to stay.
I do like the market price idea, but unfortunately it seems to complex to implement at this point in time. If I'm still around for next War, I'd like to try to implement something like this.
Question about sideboard:
"If any of the three cards are upgraded, you may reallocate these upgrades elsewhere in the deck."
Are you allowed to re-allocate 3 in-element ups to off-element, even if the starting deck had the normal max of off-element ups to begin with? So basically, to use the sideboard boost to add 3 in-element cards that you upgrade, then remove as soon as possible as a way of getting more off-element upgrades.
The deck played should always contain the correct number of in-Element upgrades (4) - the intended meaning of this rule was that in-Element upgrades can be reassigned whenever the deck is modified in between games, so:
Spoiler for Example:
Team Earth uses their Sideboard boost to field this deck in game 1.
Hover over cards for details, click for permalink
4vo 4vo 4vo 58o 58o 58o 58o 58o 58o 58o 58o 58o 58o 58o 58o 58o 58o 58p 58p 58p 58p 58p 58p 59c 59c 6u4 6u4 6u4 6u4 778 778 778 778 8pj
In game 2, they field this deck.
Hover over cards for details, click for permalink
4vk 4vk 4vk 4vk 4vo 4vo 4vo 58o 58o 58o 58o 58o 58o 58o 58o 58o 58o 58o 58p 58p 59c 59c 778 778 778 778 779 779 779 779 8pj
This is a legal modification, as it is still 50% in-Element, and contains at least 4 in-Element upgrades.
Hover over cards for details, click for permalink
58o 58o 58o 58o 58o 58o 58o 58o 58o 58o 58o 58o 58o 58o 58p 58p 58p 58p 58p 58p 59c 59c 6u4 6u4 6u4 6u4 6u8 6u8 6u8 778 8pj
This, however, is an illegal modification, as even though it is 50% in-Element, it contains illegal upgrades.
I've updated and clarified both of these rules in the original post.