Designing champions is fun. So here's an idea I've had for a champion:
Name - Juno
A young woman that duel wields short swords. The swords have chains attached to them, similar to what Sylas has.
HP - 500 (+100)
HP Regen - 6 (+1)
Energy - 200
Energy Regen - 50 per 5 seconds.
AD - 55(+3.5)
AS - 0.6(+3%)
Movement Speed - 345
Armor - 30 (+3.5)
Magic Resist - 40 (+1.25)
Passive - Unflinching Bravery:
Whenever you hit an enemy champion with an ability they become marked. Champions remain marked until you spend 5 seconds out of combat with champions.
Applying a mark deals 5/10/15/20 (lvl 1/6/11/16) (+70% AP) and lets you recast the ability used to apply the mark within 4 seconds.
Each mark applied after the first grants 4(+2 per level) bonus AD, a shield equal to 5% max HP (+1% per 50 AP) and 5 energy per second. All bonuses last until the marks wear off.
Q - Strike Through:
Throw one of your swords out in front of you. If it hits an enemy unit you will dash through them dealing 30/45/60/75/90/105 (+100% AP) physical damage to them and 50% of that damage to enemies you collide with behind them. You end up 120 units behind the target you hit.
Range - 700 units.
Cooldown - 20/19/18/17/16/15/14
Energy Cost - 50/45/40/35/30/25
W - Jump Kick:
Kick off a nearby enemy champion, knocking them back slightly and dashing 300 units away from them and dealing 70/90/110/130/150/170 (+100% bonus AD) physical damage. You cannot dash over terrain this way.
Range - 125
Cooldown - 13.5/12/11.5/11/10.5/10
Energy cost - 40
E - Splitting Strike:
Passive: After preforming a dash, mark the spot you dashed from for 2 seconds.
Active: Casting this ability will cause you to very quickly dash back to that spot, dealing 15/30/45/60/75/90(+80% AP) physical damage and applying on hit effects to enemies you pass through. Deals bonus physical damage equal to 10%(+1% per 40 bonus AD) of the targets missing HP. Caps at 500 bonus damage against epic monsters
Range - N/A
In a 1v1 she obaviously can beat an ADC like any assassin can, but should be relatively weak otherwise given her role. Her scaling is good, but her kit lacks the safety of things like stealth and intangibility that other assassins have, instead her passive is what gives her survivability and a lot of her damage (up to 160 bonus AD if she marks everyone ), but since that requires at least 2 marks it's useless in a 1v1 for that.
Energy cost - 70/60/50/40/30/20
Ultimate - In the Fray
Passive: Marking a champion grants 10/20/30% bonus movement speed for 3 seconds.
Active: Dash to a champion marked with Unflinching Bravery. You will consume the mark to deal 150/300/450 (+100% bonus AD)(+50% AP) physical damage to them and 60% of that to any enemy units in your path.
Range - 1100
Cooldown - 140/120/100
Energy Cost - 100/75/50
This champion concept is supposed to be an assassin specialized for mid to late game teamfighting, rather than early 1 on 1 dueling like most assassins. Her passive lets her spam her abilities when against a group in order to reach the backline and Survive long enough to accomplish something once there.
Her Q is her primary engage tool, being able to quickly get into a target and also past them in order to reach targets behind them. Since combining it with E is a very safe combo her E has been designed primarily as a finisher and thus has the worst base damage and stat scaling in her kit besides her passive, though obviously the execute effect more than makes up for that overall.
As for stat scaling, AP is for initial damage while AD is for finishing off targets. Her ult scales off both since it can be used for either method somewhat. I have balanced everything with this in mind. Ideally a build that specializes in either stat would be viable in addition to building hybrid. But I'm not too worried about ensuring this is the case.
During laning phase she should be relatively weak compared to most assassins. She lacks the range or safety of talon, zed or akali's Q and she doesn't have any sustain tools, so she should struggle against a lane bully. Plus while her Q's dash technically can go through minions, it's only by dashing a bit through them which may not cover enough distance against a ranged champion and won't apply a mark for the recast.
Currently her kit isn't intended for jungling and thus lacks the waveclear to do so. However I am considering changing this. Please give feedback on if it would be a good thing to do so.
In a teamfight she can use her Q to dash behind the frontline in order to reach the backline if the team lacks CC either due to having already used them or just due to the team composition. Flanking is of course an option to avoid the CC issue for the most part but going through the frontline lets her apply marks first for the bonus AD and Shield.
Chaining Q -> W lets her very quickly get distance on the otherside of a champion. If she hops over an unmarked champion this way then she can even double E the champion for a very quick burst.
All of this means that while she may not be the best at KILLING a tank, she is pretty good at bypassing them entirely.
In a 1v1 she obviously can beat an ADC like any assassin can, but should be relatively weak otherwise given her role. Her scaling is good, but her kit lacks the safety of things like stealth and intangibility that other assassins have, instead her passive is what gives her survivability and a lot of her damage (up to 160 bonus AD if she marks everyone at level 18), but since that requires at least 2 marks it's useless in a 1v1 for that.
In general her engage is supposed to be better than her disengage by a lot. Her Q is long range and dashes towards them and her ult is good for picking off targets that try to run after you start fighting them. Her E can easily disengage after the initial Q, but trying to do an all in means losing the easy out. That just leaves her W, which is good enough against immobile champions but anyone with mobility of their own can catch up to you. Plus getting into such close range if you are trying to run is rarely the best idea.
That leaves her ult as her most reliable disengage, the passive would mean you'd need to be going in for a hit in run immediately at the start of the fight, and then using the bonus MS to get out. Or alternatively after reaching the back line and doing your thing you could ult back into the frontline and use Q to dash back towards your team. But even then that requires holding onto your Q which makes it hard to reach the back line in the first place, and also has a long cooldown.
If anything I have said in the above section is wrong, that means I likely made a mistake, please point it out. If you have feedback, tailor it with the design goals I have stated in mind.
Also I suck at Lore and other non-gameplay aspects of this sort of thing. So any suggestions there would be extremely helpful.