This is another champion i've been thinking about creating for a while. She is a ranged mage that, from lv6 onward will have a humanoid form made up out of bugs by her side (hence, pusher), has a shield and a mana regenerating ability (hence, support), and carries quite a bit of cc and dot abilities. CC consists of a small 10% slow (if the creature attacks it while the target is poisoned), a 1 second silence and a 1 second AoE stun. Several of her skills also apply poison stacks to the enemy.
She deals little direct damage to enemies that can get away and know how to counter her well, but enemies that are careless can get caught up if staying near her too long without dealing enough damage. Very high burst champions will be able to kill her by simply bursting her down before she can DPS. She's also weak to enemies that can harass even harder than her, or do it from a longer range.
She can support decently with one direct support skill and one that may be used supportive, and I like the general concept of having a semi-support with skills that deal poison damage. In that case you would need to be a little careful and not steal any kills though, but I believe any good support would be able to notice when the next poison stack on the AA is up.
The passive gives a much needed early AA increase, and can give you some follow up damage with Q if the enemy overextends too far.
Q is a good harass vs. other Mages, which makes it possible for her to go mid, even with her other skills generally being relatively short ranged. it also gives the follow up damage needed if the opponent is poisoned, but as it is a skillshot, make it possible for enemies to still have a good chance of getting away themselves as long as they aren't getting caught in everything else.
W is the skill I had to think about. It has turned out to be a quite nice shield, making better lane staying power (because no health regen/lifesteal/spellvamp ability) and is also good to put on yourself for the temporary silence block for slightly better chance of getting your ultimate off correctly. It's not as powerfull as Morgana's black shield, or shield as much as AP Janna's shield, but should do the trick.
E is a nice double effect skill with the first part, the pulse, being a nice damage and only good ratio outside her ultimate. It's a self-targeted AoE going outward, which means bruisers coming in close would get the larger damage, and mages staying behind minions won't be hurt as much. The decreased damage the more minions and champions able to tank the damage will and should keep her from being completely overpowered to squishy opponents. The second effect is the return (inward) pulse, dealing only a little damage, but stunning any opposing champion caught in the area. This second part should be able to get you out of sticky situations with the 1 second stun giving you at least some time to get your skills off cooldown or just gives you a little headstart in running. I wanted to choose a chance of getting away without putting in the xx'th dash, this I feel fits nicely. If no enemy is in the zone, the skill will instead give you back the mana cost and that of allies as well, and increases her skills a bit if playing support without giving her a heal.
R is a channeled ultimate, giving her a real escape if she can pull off channeling it, and dealing a good, but not very high, amount of damage to enemies, and causing a nice explosion effect. You'd still need some skill in deciding whether you want to use your creature in or near the fights (and risk it dying and being unable to cast your active ult for quite a while), or leave it at a near highest range and risk it either walking out of your range and it dying, and/or being too far away from the teamfight after having used your ultimate.
Qu'arheen is not an official champion in the League of Legends, but is a fanmade suggestion. 
Queen of Bugs
|(Innate): Every 8 seconds, Qu'arheen' next basic attack sends a poisonous bug to the target, with the poison dealing 12 (+0.15 per ability power) magic damage to the target every second for 4 seconds.
|(Active): Qu'arheen fires a poisonous stinger in target direction, dealing magic damage and silencing any champion it hits for a short duration. If it hits a poisoned target, the cooldown of this spell is reduced to 1 second, but the silence effect will not occur again for 7 seconds. This skill also applies or re-applies the poison if the target was poisoned.
Cost: 60 / 65 / 70 / 75 / 80 mana
Magic Damage: 60 / 85 / 110 / 135 / 160 (+0.45 per ability power)
|(Active): Qu'arheen command some of her bugs to create a shield for the target champion. The shield blocks silences and it lasts 5 seconds or untill it is broken.
Cost: 55 / 65 / 75 / 85 / 95 mana
Shield Strength: 70 / 120 / 170 / 220 / 270 (+0.55 per ability power)
|(Active): Qu'arheen sends a pulse of energy outward, dealing Magic damage, dealing 10% less damage for each subsequent target hit, down to a minimum of 40%.
Cost: 60 / 70 / 80 / 90 / 100 mana
Cooldown: 14 / 13 / 12 / 11 / 10 seconds
Magic Damage: 80 / 110 / 140 / 170 / 200 (+0.75 per ability power)
Magic Damage (Minimum): 32 / 44 / 56 / 68 / 80 (+0.30 per ability power)
|(Active): Qu'arheen reverses the direction of the pulse to retrieve energy. Any enemy champion within the area of effect will be stunned for a short duration and dealt some magic damage. If no enemy champion is within the zone, recharge will instead return mana equal to that of pulse's cost, and will half the cooldown on pulse by 50%. Allied champion's within the zone regain half the mana, and will also only receive it if there is no enemy within the area of effect.
Magic Damage: 20 / 40 / 60 / 80 / 100 (+0.20 per ability power)
Mana Restored (Self): 60 / 70 / 80 / 90 / 100
Mana Restored (Allies): 30 / 35 / 40 / 45 / 50
Call of the Swarm
|Call of the Swarm (Passive): Qu'arheen calls to her swarm family to create a swarm of bugs in humanoid form. The creature must remain within 1200 range of Qu'arheen or it will lose 15% of it's maximum health each second. If the creature attacks a poisoned target, that target will be slowed by a small amount. The creature lasts until it dies.
Creature Armor/Magic Resist: 30 / 65 / 100
Creature attack damage: 40 / 60 / 80 (+0.2 per ability power)
|Transfer (Active): Qu'arheen channels for a duration of 2 seconds to prepare to transfer her essence to that of the creature and both she and her creature will not be able to move or take any actions for the duration. After the channeling is complete, the creature grows into being her, and her current body withers and explodes after a short duration, dealing magic damage and poisoning the blast zone for 3 seconds. The new her can move and take actions shortly after the transfer.
Magic damage: 150 / 225 / 300 (+0.8 per ability power)
Poison damage per second: 25 / 40 / 55 (+0.1 per ability power)