User blog comment:YourPrivateNightmare/Hail the hourglass!/@comment-8506165-20130915094720/@comment-3466579-20130915172608

The situation you have just described requires some coordination from the enemy team, and it's not very common, honestly. What if Kha'Zix follows just one second after Malphite engaging? He would be able to see you using Zhonya and he'll just wait a couple of seconds before spiking you down. With Guardian Angel, your opponents MUST take you down (and please note that as the ADC you should get some protection from your team...), then, they have to focus you again.