Change Elise's Cocoon CC-type; move around some power
TL;DR- change Cocoon's CC-type from stun to high% slow. Put the combat bonuses of Rappel onto Skittering Frenzy, make the combat bonus duration equal to Skittering Frenzy's duration (if it isn't already)
I'm not sure where Riot stands on Elise's identity, if they want her to be an assassin or a tanky-ish bruiser. But from my experience, I've always felt that she's an assassin. For her assassin tendencies, I've mainly considered her Cocoon as my tool to gap closer on an enemy or to help me escape from someone. I've never needed the stun, persay. Not even for channel interrupts, because of how clutch that play is, given that she has to change forms to use Cocoon sometimes and using Cocoon in a timely way for interrupt is gated by her form change cooldown.
So let's get on with the point here: change Cocoon's CC-type from stun to high% slow. This helps remove Cocoon's power of making its target 100% helpless, while still serving the purpose of helping Elise do her thing. Her team utility will decrease a bit, but that's okay if we're reinforcing an assassin pattern.
Compensation: put the combat bonuses of Rappel onto Skittering Frenzy, make the combat bonus duration equal to Skittering Frenzy's duration (if it isn't already). It just makes sense that Skittering Frenzy be her in-combat steroid. Loading combat power into a single spell then concentrates her power AND gates more of her power by cooldown. Her combat power in spider form becomes very apparent to her enemies when Skittering Frenzy is activated, and streamlines her usage for players.
Meddler, we've talked about Elise before. Is this a change that can be considered? Can you disclose whether or not this can even be talked about?