With this particular build, you want to have your ability rotation to be E & Q while attacking minions and W & Q when attacking other heroes. You wanna stay at a distance where you can gank the other hero while also having the option of escaping with E when you're in trouble. Best bet when using Haunting Wave is that you use it over a wall and teleport away from the hero that is attacking you. For the most part, with Sylvanas, you want to be the one that helps your team get that extra xp to stay on top of the next talent tier.