Instance Gems & Rooms

This is a basic framework for a class of temporary rooms with modifiable
stats.  Instance Gems create Instance Rooms, which may be different
areas with different monsters, treasure, and experience gain. Currently,
the rooms boot everyone after one minute and expire.

There are many ways we could use this, and I'm hoping for some feedback
before I proceed further (or if someone else wants to take it over that'd
be great).

We could have Instance Gems drop in a widespread manner, using them
to give builders 'something different' for a couple minutes - and with
increased experience gains, giving them a sort of 'quick rush' feeling.

We could have Instance Gems expire after a short time, so they're
limited solely to builders.

We could have Instance Gems given as rewards for quests.

We could make Instance Rooms that last longer, and use them as
boss lairs.

What do you think?