Bone Offering questions

Hello.
I wonder if it is possible to use Bone Offering as a main damage source. Here are some technical questions.
Let's say, a skeleton with a bone shield got hit. Shield absorbs damage and explodes.
1. What entity is the source of damage? Offering minion, skeleton, something else?
2. Is it a physical aoe spell? Or an attack?
3. Is here a way to actively hit your minions / trigger shield explosion? Seems like Fireflower with Infernal Legion might work.