You could add in an amulet that makes it so you can go in a semi-ghost form and haunt someone.
You can sort of fly, but only in short bursts.
You can also teleport to a random player one time per amulate.
One use, lasts for a few minutes, and you can still die.
However, while being in ghost form, you cannot be killed by most wepons, like swords, axes, ect.
You can only be killed by some kind of special mobs/weapons.
And if you die, than when you respawn, you have some negitive effects.