What you can't and shouldn't do is stay on healer the whole match, I like to open with attacking their tank/dps and try to bait out their stunts, then go for healer and do a stun > aoe push back > holmgang/full swing into ir/zerk double fell cleave. If their dps does not die, your team might have a dps issue, if the healer does not die or breaks out, continue chase but after a couple of minutes, you might want to switch target because that healer knows your plan.