That’s when you pop all your cds and kill him.
Sounds like a problem with reacting not the class. If he’s gunna be stupid and run at the healers punish him for it.
You and the other dps should have just lit him up for an easy win.
At the very least he would have used everything and his healer would be behind struggling due to him tunneling your healer in LoS so you’d be way ahead.