In SOR:O, each and every monster has a very low chance to drop a card of itself. These cards are solidified forms of the creatures soul granting you its power. You use a card by placing it into a equipment’s open card slot. For example, a Blade has four weapon card slots, and Chainmail has one armor card slot, lastly a hood has one garment card slot.
Most piece’s of equipment in the Upper headgear, Body armor, Shield, Garment, Footgear, Accessory and Weapon can obtain up to four slots (Ex Hood. Hood. Hood. Hood, Hood) However store bought equipment generally has no slots, or a low amount of them. Monsters tend to drop additionally slotted equipment. If your lucky you may find a rare Slot Coupon. Slot coupons come in various grades and allow you to add a slot to a equipment. Cards have some restrictions on what slots in a piece of equipment they can be put into.