Open the "pack" after asking your question for the Magic 8 Ball.
Your answer can be one of 3 rarities. Bronze (66% Chance), Silver (33% Chance), Gold (<1% Chance)
Answers 11 through 15 are Neutral answers and can be opened as packs at the link above to give you 1 new Magic 8 Ball for Bronze, 2 new ones for Silver, and 3 new ones for Gold.
There is also an about 1% chance of getting a free Magic 8 Ball in addition to the answer when opening yours.