Check out Nautilus. He is the cc king and if the pbe buffs go through he will be getting even more. His Passive makes his first auto attack on someone stun them. His Q is a hook that pulls both him and a target towards each other. His W is a massive shield that makes his aa's do AOE dmg and apply the most pathetic dot in the game. His E is an aoe slow. His ult is a targeted knockup that knocks up everyone it hits as it travels and stuns the final person. (The pbe buffs make it stun everyone it hits too)
He is the cc kinda and incredibly tanky. Plus his scalings are good enough that he can be built a mix of tank and AP if you want, or just full AP to blow stuff up. He is generally played top or support although he has a strong jg too. If you are experienced on him and are going full AP he can be a strong mid vs certain enemies.
Nautilus meets every requirement you posted minus the swarm element. Then again league doesn't have very good swarm champions. Although the Yorick rework is being heavily teased so if you were really interested in a minion-mancer (which is what he is being turned into full on) then you might wait the week or so for his rework to come out.
A few notes. Since you clearly don't have much LoL experience I would recommend staying away from elise. She is not tanky, she doesn't feel like she summons swarms, her cc is meh, and her skill floor is very hgih. She is not an easy champion to play or pick up.
You also seem to like having a form of mobility. Malz and Teemo aren't great for that. Malz is currently the closest thing we have to a swarm champion, especially if built AD. He takes a bit of getting used to though.
Anyways that is just my input, hope you find it helpful.
