Alright, so I've been making spell mods for Skyrim a while now, and I'm starting to want to do some more advanced stuff. But right now, I'm stuck. I have a cool idea, but no idea how to go about doing it.

The spell is, as of now, an aimed fire and forget type spell, If necessary I can change this. Here's what I want the finished version to do:
-I want it to do some damage instantly, when it hits a target.
-(This is the part I'm having trouble with) I want the spell to cause a damaging explosion when the NPC it's used on dies. For example, we use the spell on an NPC and the target takes some damage, but there is no explosion. Then we use a few other random spells, and the target is killed, triggering the explosion.

Any help/advice would be appreciated. Thank you in advance.