User blog comment:YourPrivateNightmare/Thoughts on the new Cassiopeia/@comment-7709681-20140914052610/@comment-7709681-20140914160128

But a minuscule, you to barely live to tell the tale, be this 10% or a flat value. If you want to condition it even further, you could make it be active only to targets affected by her Q and W, because if I say "poisoned target" could lead up have at leat another champion on the team with poison, such way that you can help her scale into the later-game (Singed, Teemo and Twitch).

However, with the new passive I have feel free to build more defensive items without guilt.