How exactly does holy symbol work now (Post bb)

If you have a level 80 priest hs'ing you at skeles, you will get 10% extra exp per kill.
If you have a level 150 bishop hs'ing you at skeles, you will get about 20% extra exp per kill, and the bishop will get about 30% of what a normal kill is worth, so total exp per kill is 150% but it's not all going to you.

x.x im still confused. So basically what is the best setup for a hs mule party for me to train with?

1 hs that can leech + xx amount of other mules who can leech + myself whos training or what?