Tried Elise a bit. Unfortunately I don't think she has any support potential because her only utility spell is her stun, which is a worse version of Taric's stun since it's a skill shot and does no damage. Plus her spider form needs items to be able to be tanky + deal damage in fights.
Her passive is kinda cool in that it encourages uses of both her forms and allows her human form to flow into her spider form as one big combo: E stun, Q W for damage and get 3 spiders R, transform, Q leap, W buff, E gap close if they flash, Q spam since it has low cooldown. How OP or UP she is depends on how much damage this combo does but at least it's way easier to do than Syndra's stupid shit. You only get 3 spiderlings out of her potential max of 5 with this combo, but it's not hard to charge them up at all really.
In terms of her skills, her human form stuff is all pretty standard: skillshot stun, single target damage skill (with a nice current %hp based boost for starting your combo), and a placement aoe skill. Her spider form is kinda like Nidalee but much more about getting in then out. I thought Q was a leap since it says "she lunges" but it's really just a single target attack. It deals % damage based on missing HP, so in theory it works well with her human form Q if comboed with after. The W boost lets you and your spiderlings dunk enemies or towers and you'll deal a fair amount if you have max spiderlings out. The duration is pretty low but so is the cooldown.
Finally her E is her most interesting ability since everything else is really basic. I thought would work like Vlad's pool sorta but it doesn't. You can only use it to get in, not out, unless there is an enemy minion or something that you can target. Essentially it's a gap closer, but you also have the choice to use it for temporary invincibility like a Zhonya's so that's pretty cool. Maybe people will find out some sick tricks you can do with it, like pull turret aggro for your team then pull out, or jump in and juke ultimates with it. The startup animation doesn't look instant though like Vlad pool so whether or not you can use it to dodge stuff easily depends on how riot coded it and I haven't really tested that.
All in all I don't know if she'll end up good or bad but at least she's waaaay better than Syndra. I image she'll be great at roaming ganks with her E stun and gap closer. Even if you miss your stun you can just jump straight into spider form and start fuckin shit up :V
Also Zombie Brand is a god tier skin
