Attention! 2%, 3%, and 4% are droppable from monsters +20.
The 7% cards are only obtainable by upgrading x10 4% cards to 1x 7% card at the NPC ‘Card Master’ in Flarine.
D C, B, and A cards cannot be upgraded.

Socket Card Upgrade

You can convert 10x lower grade Cards into higher grade Cards at the Card Master NPC. There is a success probability depending on the % of the Cards. A Cash Shop item ‘Scroll of EProtect’ (green scroll in the picture) exists to prevent the loss of Cards in case of failure. Note that you can do up to 99 attempts in one click if you put enough items in the slot.

Tip: Regarding 3% upgrades only Lightning Card 3% to 4% is worth the costs. Success rate 15%.
When you try to upgrade a 4% card to a 7% card you should definitely use a Scroll of EProtect.
Success rate 4%

All suit Piercing cards

Note: 2%, 3%, and 4% are droppable from monsters +20. The 7% cards are only obtainable by upgrading x10 4% Cards to 1x 7% cards

All weapon and Shield Piercing cards

Weapon piercing-related cards can be obtained in the Reborn and New Horizon dungeons.

Card Reshuffle System for Weapon/Shield Piercing Cards

This feature allows you to convert 3 Weapon/Shield Piercing Cards (D, C, B, A) of the same grade to a random card of the same grade. You can use this feature by selecting the menu from the Card Master NPC.

Please note that you only get the card of the same grade and you need all 3 cards to be of the same grade weapon piercing cards.