Oro's Sacrifice Questions

I got a few questions about building around



I was thinking of grabbing fire dmg, ele weapon, and fire weapon nodes to increase its dmg along with HoA while also using
to increase its dmg by a very large amount utilizing added cold dmg.

So all in all i am asking what will work with Oro and what won't?

Also with pyre would infernal blow be kinda redundant or would it be my best choice alongside say Avatar of Fire?

Ty in advance folks.

Also what would be a better starting point? Templar or Marauder? They both seem to have great starts but more ele damage is is near temp while more straight up fire and hp is with Mara. Not sure which i should go with.