This Guide is something I put a lot of effort into, i'm not at all saying this guide will work for you but it has carried me through a fair few games and is still going strong. Feel free to comment.

Well she is a bully first and foremost, if they have no CC you pretty much have your lane won already. That is if you know what you are doing. Lux is the hardest counter i have been up against so far, her shield and snare make your time very hard, Zyra is possibly the easiest, 'but she has a snare' you may be thinking. If she misses the snare she is an easy kill at lvl 2, she has no tankyness at all and Sejuani thrives off of that.

PROS:

Insane damage
Insane CC
Really tanky late game
Great ganks

Cons:

Hard countered by CC
easily kited
Mana hungry early

Here is a list of champs who counter this build:

Lux
Ryze
Morgana

Ill add more as i find out more.