The odds for pulling a Serialized card from a random booster pack is generally advertised as less than 1%. Its difficult to find out more than that for your average set, but for the LotR set, we were given a little more information
Some cards can enhance or decrease the values of other cards by dint of their own values, or of floating rules written on the cards themselves
Leading by example, the decks Commander is the Vampire Knight Edgar Markov , who is not only a strong creature on his own (thanks to Haste and First Strike) but can also provide your board with 1/1 Vampire tokens, as well as buffing your strong Vampire cards when he attacks
The original Portal: Three Kingdoms version is still $135, more than five times as much as the Double Masters printing, which is just $25
Eddie Brock/Venom, Lethal Protector (Borderless) This Eddie Brock/Venom, Lethal Protector card is another one with a comic-book cover on the flipside, and the iconic antihero is fetching a mean price at $200
My issue is that the cards ability itself isnt entirely great for knights, considering most of them have power 2 or higher