Cassiopeia's kit is just extremely outdated. From old design to simple UI flaws. She could use buffs

For instance, there is no reason for her Q to not show it's AoE. At this point if you try to see it's AoE, your mouse is only just a small reticle like a point and click ability rather than one that reflects it's actual AoE. Her Q should be like her E, in that we should be allowed to see how big the AoE is.

Then there is the decade long wind-up time on her R despite there already being an especially large amount of counter-play built into it to begin with...combined with the fact that it's her sole form of defense despite being an immobile and naturally squishy mage.

Lastly E has the most fuck-up potential. Because it only detects poison upon impact, two things can often happen. Your target dies before your E lands, sending it on cooldown, or more often, the poison disappears JUST before your fangs hit, also sending it onto cooldown.

For Q, solving it is easy. GIVE IT AN AOE INDICATOR ALREADY.

For her E, I have no idea...it should be less prone to split-second fuck-ups. Like detect upon cast or when the player pressed the E button. For R, I unno. Shorten it's wind-up like you did for MF's R?