Darkmoon Card of the North

Bottom line: probability sucks.

The Decks created are:

Chaos Deck: Reward is supposed to be a Darkmoon Card: Berserker. When struck in combat critical strike rating and resilience will be increased by 35. Stacks up to 3 times.

Undeath Deck: Increases Crit rating by 85 and each time you deal damage, you have a chance to do an additional 744 to 956 Shadow Damage.

Nobles Deck: Rewards Darkmoon Card: Greatness. It's important to note that the agility on the card is one of four possible rewards. Cards with Strength, Intellect, and Spirit also are available.

Prisms Deck: Rewards Darkmoon Card: Illusion

If you want any random full deck the first 8 tries, your chances are:
(1*.21875*.1875*.15625*.125*.09375*.0625*.03125)
0.0000001466833055019378662109375
Which means...
.00001466833055019378662109375%
( Which is close to 3/20,000,000
- or, rounded to 1 in 6,666,666)

If you want a certain deck the first 8 tries, your chances are:
(.25*.21875*.1875*.15625*.125*.09375*.0625*.03125)
0.00000003667082637548446655273425
Which means
.000003667082637548446655273425%
( Which is close to 37/1,000,000,000
- which is rounded to 1 in 27,027,027)

THEREFORE... not very likely.