On Famcraft, players can bottle their xp for safe-keeping. We have had this option for a very long time, but a plugin update has allowed us to modify some of the mechanics of this feature.
Now, to bottle your xp, simple SHIFT-right-click on any spawner cage block.
As always, you will be charged some of your xp when you bottle it, but now you should l be charged a slightly lower percentage than before.