https://www.twitch.tv/lck1/v/87297687
Watch 01:55:44.She did one shot to Kennen with 2 kills.Meanwhile Kennen had 6 kills and Abyssal.Lissandra needs damage nerf.Her damage is unacceptable.She has Annie's damage and ultra CC.
Also she has 90% p/b rate on patch 6.15 LCK.
EDIT:There is no counterplay.
i don't think she has any issues, outside of LCS. A win rate of 47-49% does not indicate anything too overpowered. Cooldowns are long, base damage is low. In solo queue she struggles to use all her CC to full potential with random people, in LCS that's another story. For the rest her one shotting a squishy is nothing too different than a Leblanc one shotting a squishy. Also abyssal is not a spirit visage, and kennen having 4 more kills than lissandra does not give him 20% more damage reduction or anything.
On the contrary there is counter play to her. I'm not trying to say she OK but she definitely has counter play. Her biggest counter play aspect is the fact that u can tell where she's gonna port in and how a team can CC and burst her the moment she pops in (not the easiest thing to do but it can be done)
Lissandra needs more than a nerf but a rework of some sort because her main issue is the amount of CC. That lissandra was fairly big and any champ with that much ap will burst you down instantly, that's what ap does on mages. Generally speaking her burst is less of an issue since her cc can generally mean free gank, so her all in on her E could use a speed nerf to give players more of a chance or a mini self silence to sort of tone her down. There are a few things she needs but increasing her mana costs won't fix her issues, they will only Bandaid the problem temporarily.
As a Lissandra main trust me she does have counterplay, using this one clip and saying she's broken is like seeing a Sion 1 v 5 pentakill and demanding a nerf. She does do good damage but shes not broken, sure she does a lot of damage but so does any mage with lots of ap, yes she has a bit more hp than other mages like 
or 
but she is a bit slower as well, when playing against someone with speed burst and slows such as 
or 
I never stand a chance because they go all in and even with my root their slows basically imobalize me. All of her abilities are on such high cool down as well, he kit as a whole does a lot of damage but she'll usually miss out on her E damage since she'll use it to get to you and ult. She's vulnerable to ganks as well since without her E she has very low peel
