Riot, your game is in dire need of a specialized training mode.
I don't mean like the barebones starter training you have, I mean something more like this.
https://www.youtube.com/watch?v=TiLZ28RJe18
Customized, specialized training sessions for X aspect of the game, be it general training. (Complete X minion waves without missing a single CS, then up the difficulty by adding bots harrasing you and so on) or dedicated to X Champion (Successfully land a Rumble's Equalizer on the 3 enemy Champions running away), and so on.
I mean, even in your most recent Champion spotlights you can see that you can setup different scenarios when you are showcasing their abilities, you just need to actually put effort in it, because let's be real, the more time LoL has, the steeper the learning curve becomes, and while it isn't a big deal for old timers, newcomers might have a hard time adapting, also that kind of "training missions" would help every one of us to hone our abilities, and you can throw incentives for completing/grinding them and whatnot.
I suppose it'd be a good idea to put the sample list in the main post, so here it goes.
Generic training missions
Minion - Complete X minion waves without missing a single minion.
Minion - Freeze the minion wave.
Minion - Make your wave push the enemy one by killing off X number of enemy minions.
Turrets - Draw and drop turrest aggro, your allied bot will back off from the turret's range as soon as they receive a hit, the goal is that neither die.
Flash - learn to flash over walls.
Flash - learn to flash over X abilities.
Orbwalking - You cannot issue 2 AA's in a row without moving your Champion between commands.
Advanced orbwalking - Learn to kite a meele Champion.
Champion-specific training missions
Rumble - Launch an equalizer over the 3 enemy champions when they are aligned.
Zed - Use your Ultimate and abilities on the enemy ADC and burst it down, then return to safety before the enemy team kills you.
Nami - Land the godamn bubbles.
Team-oriented missions
Teamfighting - Wait for the allied bots to be in position and have their cooldowns recovered before engaging with Malphite Ult.
Splitpushing - Using the three available wards in your inventory, set up a vision field so you can splitpush while your allied team holds the enemy, make sure to know when to flee so you aren't caught.
Turret defense - Use your abilities and poking potential to thin down the enemy minions and weaken the enemy until they are forced to retreat before your tower falls.
Peeling - Use your stuns to save your carry from otherwise inevitable death from Zed's ult.
And so on.
