From http://dev.bukkit.org/bukkit-plugins/fun-hard-mode/tickets/99-making-the-lapis-lazuli-and-bats-interesting/
Reported by bigscary:

Any thoughts? Maybe killing a bat with an arrow from a distance drops a lot of extra EXP or some arrows? That would be fun to try and hit a bat like that - a real skill test.

For lapis, maybe getting a whole lot of it could make a diamond...? To compensate for it being sometimes ridiculously hard to find diamond when you can't break stone?

Diemex:
I planned on adding bats to tue summoned monster of witches. Makes sense right? Also potentially add Ai to them making them attack you. For lapis: I use it in another plugin called KeepXP which I believe is on my jenkins. That plugin allows you to save your experience in glasbottles which cost about 4 lapis blocks. You can also adjust the cost.