Tip : Never count on DOT's to finish off riven or tower hit
Playing vs other champions you have hope that your ignite kills them because it normally does, not riven. You'll just see her dashing on your death screen and shield up to tank that ignite/tower hit. If she has life steal she'll more than likely be full health and kit ready ( not R ) to fight off the jungler too if he/she comes to clean up.