Hmm could Rake or anyone explain this better? I think I didn't understand. 
There will be a specific table that explicitly specifies which attributes on a card from the main deck will allow you to choose attributes on cards in additional decks. This will also be available to players, but in a more clear and simplified form, in the compendium.
To give you an example:
Card #1 of the main deck has the following attributes:
1. DEX
2. STR
3. STA
4. PATK
With these attributes, in an additional deck the player will be able to have ONE of the following attributes:
1. DEX → STA
2. STR → HP or PATK or PDEF
3. STA → INT or PDEF or STR
4. PATK → MATK or WIS or STR or HP
You may notice that a bunch of attributes on a card from the main deck (dex, str, sta, patk) will make a card in an additional deck for the magic class (sta, hp, int, matk) or for the tanking class (sta, pdef, str, hp) or for the healing class (sta, hp, pdef, wis).
But for the example, I took a quality combination of attributes on a card from the main deck (dex, str, sta, patk). If I had randomly chosen attributes, such as (dex, mdef, int, patk), I would be unlikely to get quality attributes when choosing on an additional deck.
All this is just an example and to explain the principle in more detail.