What if we reworked Cassiopeia's passive?

Can we, please? :D

What if it was something like this

Serpent's Curse

Enemies hit by Cassiopeia's abilities gain a stack of Serpent's Curse. Affected enemies take Z% bonus damage from Cassiopeia. This effect lasts X/X+1/X+2 seconds (values at levels 1, 6 and 11) and stacks Y times. Twing Fang's damage is increased by (Z+Z)%.

And then you can rebalance her abilities' damage values accordingly. Oh and remove the damage amp on E. And the mana restore on E. And change her mana costs. And make it so Cassiopeia is healed for a certain amount depending on the number of stacks of her passive the target has when she hits it with E. And make her Q's cooldown be 4/3.75/3.5/3.25/3 seconds. I mean, while we're looking at her, why just stop at her passive, am I right?

What would this accomplish? Several things, actually!

1. We get rid of her current passive. That's a good thing, because her current passive is honestly just bad design. It does not offer any interesting additional gameplay elements to the character, unlike her previous passive. It's just a ball of meaningless stats. When you get your passive upgrades, it doesn't feel like you're getting stronger, it feels like you're getting less weak, like her power was just locked away as a big F-U to the players. It makes zero sense thematically. Even though you guys at Riot have tried really, really hard to sell the idea that Cassiopeia is all about growing and ascending, she's not. She's all about destroying her enemies. I constrains her ability to build items. Cassiopeia is forced into a very singular build path and your biggest choice here is which mana stacking item do I get? I mean I get that you guys wanted her to be a pseudo-marksman, but did you REALLY have to also port over the very sad fact that AD carry itemization is insanely stale?

2. We get an interesting passive that is pretty much the opposite of her current one. It adds more depth to her kit. Maybe too much? IMO no, but I could see why some would argue that point. It's got a clearer power curve because of the increase in duration + your damage also scales with base damage and GOOD ap ratios instead of trash ones that are only justifiable because of the 500 stacks bonus. It makes a lot more sense thematically. It brings back the item diversity Cass used to have that the rework completely dumpstered.

3. It allows Cass to adopt two playstyles, poke and all-in. You can poke with Qs and you are rewarded for landing several of them (the damage values would have Qs deal less damage without passive stacks, but more with max stacks). You can also go all-in. Since Q would only apply 1 stack per second and E benefits TWICE as much from the passive damage amp as well as applying it 2 times per second, the all-in style is rewarded more than the poke playstyle, because it is of course much riskier. This is very important because one of the things the rework did was remove the ability to kinda switch roles on a whim. Before the rework, Cass could poke until she was ready to go in OR go in as soon as she hit a Q, depending on what the situation called for. Now, the only good decision is to go in (unless the enemy jungler is in that river bush ;P). This, along with her item diversity, made her really interesting and fun to play. You could go for the poison build with Rylai's and Liandry's and still go all-in, or you could go tanky AP for a Ryze-esque playstyle or super heavy AP for the rambo twin fang spam. Of course, the 1st build would not be as good at all-ins and the last one would not be as good at kiting and zoning, but you could CHOOSE.

As for the other changes, namely making Cass' healing dependent on her passive, the removal of her mana restore and rebalancing of her mana costs and the change of Q's CD make her less of a lane-bully. Ideally, the passive would last something like 4-5 seconds at levels 1-5, so unlike old Cassiopeia, you can't just Q, Q, Q, Q until they're almost dead because hitting that one Q every 10 seconds or so is not nearly as rewarding as it used to be. As for current Cass' very annoying lane pattern, which consists of hitting one Q and eating half your health bar, it can no longer be sustained (lol) because you can't technically have infinite mana AND easy sustain through last hitting with E. IMO, having to juggle your mana like any other mage makes for a more interesting laning phase for both the Cass player and the opponent. Does it make her unable to lane? Of course not, that's not what we want. Besides, you can't really ever expect Cass to be bad in lane without being utter trash but you CAN balance her out to be only decent before she takes off WITHOUT giving her crippling mana costs.

tl;dr Just read the first few lines