Porcellio Card ??

[Former-GM-Vanadis]

Whispers, your math is wrong.

The probability of getting atleast 1 card is the compliment of the probability of getting no card, thus the formula is

1-(0.9997)^x

where x is the amount of kills.

So for 5000 monsters, it's ~77.7% probability to get atleast one card.

But even so, the next monster will still only have 0.03% probability of dropping the card. And killing 5000 more monster will give you a 77.7% probability of getting atleast one card.