How has this relatively new spell changed ur game? As you may have heard I've been playing LeBlanc recently, and I've found that subbin' Ignite for Promote is pretty good. LeBlanc has never been a great pusher and I find that mid - late game it really helps to round her out. And also kill at least an additional 30 minions per game and TONS of turret damage.
I was just playing vs Lux, and Lux could not out push me, because whenever she got closer too my turret I'd promote minion and boom, right back where she needed to be.