I’ll share the only build I could make her work really well.
Level 1: Thunderstroke.
Level 4: Inner Light.
Level 7: Surge of Light.
Level 10: Either ultimate.
Level 13: War Matron.
Level 16: Static Electricity. (major power spike)
Level 20: Rockstopper.
[T1331124,Cassia]
This is a build that a friend of mine shared with me and he said was quite op. I tried everything basically, full Q, full AA, some mixed talents, but this one was the best one BY FAR. Like, it is extremely good.
Your level 1 is the Q quest. This not only boosts your Q damage, but also grants 5 armor on your trait. Even if you lose trait, you will be just spamming Qs and getting the armor back very fast. You also don’t have to worry about AAing the enemy that much.
Your level 4 is just a nice sustain/protection. 25% of her hp is quite a lot and you reduce the cd of it by 10 sec for every Q hit. You are basically spamming them, so this is good.
Your level 7 is the same as before rework, just really good burst. Cassia is still quite melee with 4.5 range, and this is good when you are playing close. It is also pretty easy to stack, and with armor on trait you can even stack on towers a bit.
Your level 10 just depends on what you like. If the enemy team is playing way far back, you could take Valkyrie just to catch someone and blow them up. If you are don’t need that, I’d say just go for ball lightning and use it when the fight starts for extra burst.
Your level 13 gives you protected btw on your E. This is good to soak some damage. Damage soaked also counts towards surge of light at 7.
At level 16 you have your major powerspike. You get +2 charges on your Q, so now you got 4. You also throw a Q on nearby heroes when you use Fend. THIS IS SO GOOD!!! This helps you stack your level 1, this deals incredible extra damage, this also reduces the cd of your level 4 healing. It is just amazing!
At level 20 you get armor just for more protection. It is on a really short cd (30 sec), the armor is pretty good and it fully charges your trait, so if you drop it you can use it to get it back instantly.
This is the game I just had with it:
Well, unfortunately I didn’t have the same success with other builds and they might need buffs, but this one is really really great.