delericho
Legend
Is this normal practice? I've been gone from the game for some time and I'm relearning but I always remembered the DMs letting you use your gold as you wanted to - as long as it was legally acquired.
This was more or less standard practice in 1st and 2nd Edition, much less common in 3e, less common still in 3.5e, and certainly not standard in 4e.
However, there are two other factors at work:
1) When you purchase a magic item, especially one from a supplement, you should probably inform your DM(s) of what it is and what it does, as a courtesy if nothing more. It must really suck to put lots of work into a storyline, only to see it trashed by an unforeseen item power.
2) That said, the DM(s) need to take PC powers and capabilities (including magic items) into account when preparing. If they did know about the item before introducing this plot item, then they goofed, and have nobody to blame but themselves.
Fundamentally, you need to talk to your DM(s) about this. The players and the DM(s) really need to be on the same page about things like this... and it's really not right for them to unilaterally impose a restriction of this sort on the game in mid-stream.
It's also worth pointing out to them that it's not the "Adventurer's Vault" that's causing the problem here. It's one particular item you happened to have. If they're going to ban that, then they're probably also going to have to ban "Martial Power" and other supplements for exactly the same reasons.
(Of course, in 3e I always completely banned anything from any supplement I didn't personally own, and always advised others to do likewise. However, 3e had more balance issues than 4e... such a move might not be required in the new edition.)