What do you expect/hope Nexon throws in with Big Bang?

As far as I know theres no such limitation...the only one I know of is that you cannot resell an nx item you bought from someone else. I will try to test this though

There is that limitation. If used in any way, or traded, NX items become untradeable. Also, something that is a little less obvious, but if you use anything in a stack (say bundled owls or EXP charms) then you make the rest of the stack untradeable as well. With NX, stacks are all or nothing.