Cassiopeia

Ok, I've played her since Season 2. I would say a total of 500+ games. This is my take on her

Pre-rework, she was more safe. Her Q ratios were higher hence in lane, you could spam (thanks to passive) her Q. It was a safe way to fight without putting yourself in a position to trade. If you wanted to trade because you know you were stronger or capitalizing on enemy CD/mistake..etc, you can go in with her E. Some people referred to her as a poison mage once champions like Yasou, Vi, Zed..etc started becoming more common (assassin meta). So most players and guides suggest you max Q instead of E because it was safer, DESPITE THE FACT that overall damage went down doing this.

The rework was suppose to "fix" that. It did, but it created a lot of other problems. Her current state is that her Q is pretty weak, you are somewhat expected to use E to trade. Then re-use E to get you health back up (it now has spell vamp) and her mana (it has mana refund+). The idea is pretty good. They also fixed some issues that pre-rework cass had with her E poison detection and her ult hit box. What the re-work did wrong was stuff a huge amount of unnecessary stuff into her passive. It makes her into the ULTIMATE feast or famine mid laner. If you are winning your lane, your E will melt even the strongest tanks. If you are losing your lane, you will likely be dived constantly by enemy because your E is really weak.

At the end of the day, Cass feels like an ADC (and she should, that's her design). But she doesn't have all the benefit that ADC champs have; free scaling, life steal, and a support. She has an inferior life-steal version, it's spell vamp. She has gated scaling. She also has no support so she must rely on her own abilities for peeling. Is she strong? Yes, just don't lose your lane, or you will feel the "famine" version of her kit. In this patch, she is a bit stronger ONLY because she is very strong at kiting non-mobile champs like Tryndamere who are being picked a lot. You can literally kite a Tryndamere around the lane with no problem, and as the game continues, it only gets easier. Her itemization is pretty static and has not been hit hard by the nerfs. However, games are shorter so being that she is has a gated scaling kit, you really wont see it a lot. Her passive (all three) will normally be up by ~28 min into the game. Games tend to end at about 20-30 min. She is hard to use because in team fights, all mobility make it very easy for you to miss one crucial Q and it will hurt a lot. Your E can't be spammed. If you plan to play her, play her vs enemies that can be kited, like Singed, Tryndamere, Yas, ADC with no mobility, and avoid enemies like Talon. Good luck

Without a doubt though, there are many mid-laners who require less from the player but still give better rewards. I suggest you stick with those till they fix cass' feast or famine state. Diana, Veiger, Brand, Lux, Malz, Viktor, Ahri, Anivia, Fizz, and Yas are all in better state than she is.

Don't play a champion for strength, you can still enjoy a playstyle even if the champion is slightly weak.

You might be surprised by some of her strengths, like lvl 2 and 3 cheese.

But.. as a Cass main, I have to say, she's not looking too good right now. ADC's rule the game and Cass doesn't snowball LIKE A NORMAL CHAMPION because her stupid passive restricts her.

No. I would not buy her with real money. Ip is fine but she is not very strong right now.