I believe that "It can be flamed" rerfers to the fact that the key itself is burnable. To get past the barrels I believe that you have to push them around in the exact right way, but I'm not sure as I haven't done that map before.
... it seems, many pupland maps are almost 10 years old, perhaps some functionality got lost with server changes ... I took a closer look with the java map editor:
- The key in question should unlock a weapon room. But the key seems unreachable.
- At the lowest (?) power plant level there is an island which seems unreachable - unless there is a possibility to walk on water.
- At Heinrich's cave Heinrich blocks access to a bashable wall. Seems a bit "out of role" if you have to slash Heinrich to gain access.
But after all - I'm still newbie and may overlook methods ...
I have the right stuff,
and my decision is that most of pupland should be incrementally overhauled to make the story more understandable, and include more adventure .