I always thought you absolutely needed an Ace to make a deck but looking at the serpent deck I noticed that there is one combo where you do not need an ace. Is this right? Also, is it really just 7 cards? I thought you needed all 8 cards to make a deck, but again the below shows only 7 card combos.
You do indeed need the Ace for all decks. Wowhead does not list the Ace because it is only showing the "mats" for the creation of the deck. Wowhead is assuming that the Ace is using these "mats" to perform the creation. Most of the items on Wowhead look like this.
If you look at each of those that were listed on wowhead, there are 8 total combinations. Each combination corresponds to you clicking a different card to build the deck. Any one of the cards can cast the spell to make the deck, but each one is a different spell ID depending on which card you clicked to make the deck. The reason it shows a card missing in each is because that is the card casting the spell and in order for it to cast the spell it needs the remaining 7 cards to be present.