Cassiopeia's Passive and Miasma

Hello, since the mid season magic update hit the PBE I've been keeping a close eye on Cassiopeia's threads, comments and streams and such, and I have a few concerns! (Text taken from S@20)

Serpentine Grace (Passive) [REWORKED] NEW EFFECT: "Cassiopeia gains 4 Movement Speed (4 per level). Cassiopeia cannot purchase Boots items."

How would this passive work with % Movement speed increases such as MS quints or Luden's Echo? And if this passive is to enhance her serpentine thematic of being slippery and you know....a Snake, isn't it possible to add a slow resist (Like swifties) when she reaches a certain amount of movement speed or reaches an amount of AP? Since she can't access slow resist in any other way than from Swifties. Having Swifties with Cassio was super useful because of the kite+Chase potential

**Miasma **(W) Mana cost increased to 70 at all ranks from 40/50/60/70/80 Cooldown increased to 22/20/18/16/14 from 14/13/12/11/10 "Cassiopeia spews venom in an arc in front of her, leaving toxic clouds for 4 seconds at max range or at terrain hit.
Enemies in the clouds are continually afflicted with Debilitating Poison, slowing them by 35% and grounding them, prohibiting the use of Movement abilities. They also take 20/35/50/65/80 (+0.15) magic damage per second."

• Slow now 35% at all ranks from 25/30/35/40/45%.
• Now fires multiple clouds in a large arc that lands at max range (800) or first terrain hit.
• Now GROUNDS enemies in cloud, preventing them from using movement abilities** while** in it.

My main concern (and of a BUNCH of people that have played her) is Miasma. I get the thematic of being cornered by a Snake, you can either face her and get ulted, or pass through it and get crippled. The terrain collision doesn't bother me at all, I think it's understandable since she spits poison in a direction. I also understand not wanting to enable the Cass player to use it at pointblank range because she needs a weakness against divers or people that can gap close/blink to her effectively or work around the range of the skill, HOWEVER, a fixed range of 800 removes decision making and playmaking potential in my opinion, so why not add a minimum cast range of say...300 and allow us Cass players the possibility to decide where it lands between said range? Think of a ring AoE, The arc could be more "circular" at 300 range and spreads out until it reaches 800.

The skill, despite being a "nova" type skill, doesn't even have Champion collision, and It doesn't interrupt dashes already happening like Poppy's W does, The zone control is exclusive to the 800 range, while old miasma didn't have this handicap. In the video, Vi doesn't even let go of her Q (it gets cancelled of course), but I believe that if she let go before stepping on W, she would have gone past the AoE just fine, since it doesn't interrupt, and the slow wouldn't have lingered on her so she'd be "safe" from Cassio's fangs.

Another issue the skill has, the poison doesn't "linger" after leaving the area, this is completely anti thematic, Poison IS a "lingering effect", even after finishing contact. I think that either the "grounded" effect or the damage should linger a bit after leaving the area for at least 1 second, OR, targets poisoned by Noxious Poison from Q AND Debilitating poison from W should get an additional "poison" effect, possibilities are endless here. Mini root, mini stun, movement speed steal, extra slow, MR reduction, etc.

This is just my grain of salt for a champion I love and would like to see succeed and carried to it's full potential, thank you!