Booster card pack is an item from the Agent V.I.P that can be purchased for 5,000 Donation credits. When consumed, players gain three booster card packs. There are currently four types of booster cards: Luck, drop, accuracy and damage boosters. These boosters come in three tiers: Weak, normal and strong. The booster cards last for 60 minutes upon activation. Players can not activate the same card twice to double the duration. Instead, it will give them the option to reset their current timer.
The difference between Luck and Npc drop rate is that luck also applies to upgrades, clue scrolls, box/key openings, etc. while npc drop rate only improves drops from monsters.