Bukkit

What is the enhancement in mind? How should it look and feel?

The wither's attack is an easy way to give mobs an extra attack,
MANY plugins utilize wither skull attacks to bring more mobs to their plugin. You should try it out.

AKA, a way to make yer wisp attack, witherskulls shooting out.

There is a guy who make a TARDIS plugin, ( it's from Dr. Who ).. but he actually coded one of the worlds to spawn squids that fly, and shoot witherskulls as their attack, you should check it out. I have it loaded on my server if you ever wanna check it out.