User blog comment:BerryBandit/Mechanically demanding champions/Quick decision champions/@comment-6906412-20130623223346

I think Syndra is probably the most difficult champion (but one of the most fun) in terms of mechanics. Syndra makes Orianna look like a walk in the park when you compare effective use of spheres to positioning of the Ball.

Twitch, Vayne, and every other ADC aren't so much about skill or reaction time as positioning, and it is up to both the ADC and the team to make a safe "pocket" in which the ADC can pound down the enemy without dying.

Lee Sin definitely takes good mechanics and fast fingers to Sonic wave/Safeguard combo to harass/maximize utility. He also requires skill management to maximize his passive (energy regen/AS boosts).

I don't see why Kayle is so difficult. As far as AP mid/top Kayle is concerned, it's a matter of throwing out your damage and using your heal and ult on priority teammates (or yourself) to stay alive. Support Kayle is a different story, where you have to balance mana usage for CC, harass, and defense.

If you want a "twitchy" fast-paced character that requires good reaction time, play Katarina. When played effectively, Katarina is terrifying and awesome, capable of easy doubles, triples, and more.

Ahri is another decently fast-paced champ who can make amazing plays with her ultimate whether it be jumping in and out of a fight over walls or lining up a clutch charm.

Elise and Jayce are also micro-intensive characters who have two sets of three skills, one melee and one ranged each. Elise has the weirder overall kit as her skills don't mesh as nicely as Jayce's do, but both require efficient stance/form swaps to maximize damage of each skill.