I'm doing a Lich playthrough first time, and I've got a question about the Lich spell Bonespear. According to the spell descritpion, if you kill something with the spell a bone spear (imagine that!) is created, and you can fling it through a line of enemies for lots of damage.

I've cast it, killed something with it, and the spear is just sitting there in the battlefield...so that works. My next question is - How do I use it? Does the spell actually work as described, or is the spear just for show?