So what can credit card NX be used for?

http://billing.nexon.net/WZ.ASPX?PART=/P...ng/Account

specifically:

NX Credit Restrictions

In order to fight fraud within our games, please note that gifting is not allowed with NX Credit. Below you will find specific restrictions in each of our games.

MapleStory


Character Name Change, Character Transfer, and Cash Shop Surprise cannot be purchased with NX Credit, nor can NX Credit be used in the Maple Trade System (MTS).
Gachapon, Remote Gachapon, and Vicious' Hammer cannot be purchased with NX Credit until level 30.