kill 999 of any type of the same monster = Force spawn number 1000
that number 1000 will have a 100% chance to drop their card if you have never gotten that card before.
the card will be an untrade-able version of the card. any gear you socket that card to will become untrade-able.
the monster will not have kill assist and if you die you will lose 1 count out of your kill count for that monster.
once the quest is finished you cannot do that quest again for that char for that card.