User blog comment:Tayzer/My own league story: supports/@comment-4484912-20131230020657/@comment-4814368-20140102224833

This is all great advice. I play a LOT of Janna, and her shield really helps carry or herself live through a stun. Most importantly though, her twister and ultimate let you delay or reset those hard engages wonderful. A stun is worthless if the enemy damage dealer can't get into positition to capitalize on it. A really well placed ult can also separate the dive-heavy supports from their ADCs, which is a great way to start a turnaround.

Keep in mind though that a lot of your counterplay also depends on your ADC. If the ADC and you can dodge Leona charges, then your job is much, much easier. If they keep over extending, not setting up counter-ganks, etc, then you're playing a losing game regardless.