The XP Cannon can be placed. When right-clicked on, a GUI opens up. In it, the player can supply it with XP Crystals. 1 crystal equals 50 shots.
How it works
When fired (shift-right-click or redstone signal), a green orb shoots out. It will fly in an arc like a Snowball, except when it hits, it will spurt XP all over. It will also do 10 damage to any things caught in the XP spurt.