In a teamfight?
Let's say the enemy team is composed by:
Support (Core guardian, healbreaker or tempest).
Ranger at first of the match goes home(close) node.
Rest is mid.
I always find confusing on who to focus first.
If you focus the support, he usually start kite around and defend tank himself not to die while the others just freecast and focus back on you.
If you focus the necro, he gets supported and become usually too tanky to get down.
Of course I am not talking of a team with microphone communication and top pvp players, but general target focus on tournament pugs, soloQ ranked matches where most of the times target focus is pretty meh.