Any immobilizing from nearby allies adds plasma, not just roots. Her ability preview shows all of Leo's stuns adding it, and I've had it work with Janna tornado, Lux Snare, and Brand stun.
And the Q targets whatever is closest to you. It deals a ton of damage when upgraded, particularly against isolated targets. And since as Kai'sa you have such a great way of reaching backline targets, the counterplay to her Q burst is to make sure you aren't alone (just like another Void predator, Kha'Zix).
She strong...when played well, and with the right support. Your laning phase is very precarious, as you need items in order to become a threat. If I may, some tips I've found from my plays on her:
##Supports:
You want either tanky, or poke mages. Tanky, as they have a ton of CC to stack up your plasma for you to burst it (and for the peel). Poke mages, as they can get the damage off against the enemy while you concentrate on farming, and when they are low, you both pack a punch to get the kills
##Build:
I've been starting long sword + 3 pots, taking Fleet Footwork as my keystone, with Overheal,** Bloodline**, Coup de Grace, and then Manaflow Band and Gathering Storm as my secondary path runes. This gives you the sustain you need in early laning, with the setup to be self-sufficient and a carry as the game progresses.
For items, my first buy is turning the long sword into a Bilgewater Cutlass for Blade of the Ruined King, picking up an early Greaves for the better trading and farming. After that, I go into Infinity Edge, making sure to grab the B. F. Sword and Pickax first. This now gives me my Q upgrade, and I'm near to my E upgrade next. Finish up IE, then build into Statkk Shiv (preferred order would be Zeal and the dagger for Kirchie's Shard, as that now gives you enough bonus AS to grab your E upgrade). Last items are flexible, from a Last Whisper upgrade, to a Mercurial Scimitar or Rapid Firecannon.
Skill order, you want to get and max your Q first, followed by E, and lastly your W. Obviously level R when you can.
##Play Style Patterns:
Now, this could largely all be about to change with her buffs coming out, but I can see this for what it's currently like, as it will likely at least be somewhat similar.
For the most part, you just want to play it safe and farm, letting your support poke them. An enemy lane that just lets you farm is a dead one once you get your items. That's not to say she doesn't have lane duel power. Your Q can be fairly decent harass, even pre-upgrade. Sure it's not much, but it's a bit of chip damage that can start to stack up. You want to make sure you are being anticipatory with your E use, as early levels the channel is reasonably decent, so you don't want to suddenly not be able to attack in the middle of a fight. However, don't forget to use it, as while the channel is bit tedious, the MS buff is great for dodging key CCs or other abilities.
Some good trade patterns are to let them step up to farm, and grab a few autos or Q hits. If they are also CCed by any means, activate your E to grab a few chasing shots as they retreat. Then if you're free, throw out a final W for a decent hit of damage, as well as a possible passive burst if you managed to stack it up high enough
Well, I hope that was informative enough. I've played for a decent bit (at least, from what I have time for. Work is no fun -_-), so I'm glad to share any tips or info that I've learned. If you have any extra questions, just let me know, and I'll see if I've got the answer! https://static.gamespot.com/uploads/original/1551/15516851/2941768-lfs17.png
