[Champion Concept] Illyana, the Mirror's Edge
This idea was actually based on a dream I had - a house of mirrors (you know, the ones in carnivals and stuff) where you always feel like someone's following you, and at the end of the maze, when you think you're finally out, someone kills you from behind.
Note: I'm aware that the numbers on the skills are badly balanced. This is more of a kit overview more than anything else, and numbers can be changed accordingly.
Lore Note: This is a TL;DR version. If you want to read the entire story, click HERE!
Member of a troupe of treasure hunters named the Dancing Daggers, Illyana was the best they'd ever seen. At her coming of age ceremony, she and two others were hired by Demacian nobles to conquer the Baron's Jowl, a mysterious dungeon that appeared near the Shadow Isles.
After encountering a dark wizard, her two brothers fell in battle, and Illyana's cry awakened her latent magical talents, merging the souls of her fallen brothers into an ancient magic dagger. Using her new-found powers, she defeated the wizard and the corrupted, possessed Demacian nobles, emerging from the dungeon as a new woman.
Returning to her tribe, she vowed to not let the death of her comrades be in vain, and decided to leave the treasure hunters behind in order to fight against death itself.
"For some, Death is a destination. To me, it's a target."
Full Name: Illyana Ashitari
Race: Human
Place of Birth: Dancing Dagger settlement near the Shurima Desert
Current Location: Unknown, presumably somewhere in the Shadow Isles
Weapon: Translucent, almost transparent dagger. Left-handed.
Physical Traits: She's 5'5", and has long, thick dark brown-to-black hair, braided. Olive skin, piercing dark green eyes, fair proportions. Lean, lithe, and flexible. Wears a white cloth cap, dust-brown cropped top with a white undershirt. No sleeves. She has half-pants - as in, one side stops at her thighs, the other goes down to her ankles - somewhat skintight, and they are a darker shade of brown than her shirt. dark brown utility belt and silver buckle. Scabbard for the dagger on her right hip is adorned and gilded. Dark yellow/light brown cloth shoes. Wears dark brown shoulder pads, kneepads and shinguards.
Champion Select Quote: "Time heals all wounds - except for death."
Moving "Wait for me..." "If only I was stronger..." "I can only go forward." "Until the end... and beyond" (Buzz Lightyear reference) "We walk together." "The end is only the beginning." "Look closely." "Stay alert." "The shadow approaches."
Attacking "Perish swiftly." "Death awaits!" "I'll show them my pain." "My darkness beckons you!" "They can't keep up with me." "Your life ends here." "End of the road."
Spell Specific Q "Illux!" "Let's do this!" "Brother!"
Q Swap "Too slow!" "Need a hand?"
W "Go forth!" "Basset!" "Take them out!"
W with Q active "Brothers!" "Together!" "Now!"
E "Can't catch me." "Can't touch me." "Can you follow?" "Watch closely." "Get ready!"
R "Good night." "Care to join me?" "On mirror's edge." "It's time."
Taunt Illyana creates a copy, switches with it, and then they both attack in an x. "What doesn't kill only makes you stronger. But you're already dead." "You better watch closely, or you'll never see me coming.
Joke She creates a copy, then jumps offscreen. The copy disappears, and she falls back down. "You can't see me." (John Cena reference) "Made you look." "Up high! Down low! Too slow!"
Dance Illyana does the Michael Jackson lean (from Smooth Criminal), to the left, then the right.
Champion Specific
Joke with 
: "Maps? Hah! I don't need those, either."
Joke with 
: "Watch out for snakes. Sneaky little things."
Joke with 
: "So you like playing with your shadow, too, huh?"
Taunt to 
: "Only cowards rely on others for revenge."
Taunt to 
: "I will free those poor souls."
Taunt to 
: "You would give up your own humanity to escape death?"
Taunt to 
: "Souls should never be enslaved without their consent!"
Taunt to Kindred: "I have been searching for you... for a very long time."
Others' Spell Specific Revived/Protected by Zilean/Kayle Ult: "If only you were there back then..." Surviving Karthus Ult: "Not this time." Soraka Ult: "I wish my brothers were here." Ulted by Mordekaiser: "You cannot take me!" Ulted by Yorick: "This feels strange." Taking Thresh's Lantern: "Just this once, fiend." Becoming Oathsworn with Kalista: "I have no choice." Ulted by Kalista: "I will not thank you."
Upon Buying an Item
or 
: "This does not feel right."
: "Tsk. Cursed thing."
: "I can feel its power."
: "Reminds me of simpler times."
: "Death will never catch me."
: "Why did I buy this?"
: "A necessary evil."
: "I prefer blades."
: "This will hurt."
: "If only I found this sooner..."
: "The coward's weapon."
: "I could have saved them..."
: "This draws too much attention."
or 
: "I feel selfish..."
: "Perfect."
: "How do I even hold this?"
: "One with the shadows."
Allies:
Enemies: Kindred,
Antagonistic, but not outright Hostile: 
Pairs well with: 
CC, CC, and more CC - Illyana can pull off great feats of strength if she can set up her skills properly, and friendly CC is all she needs to get the ball rolling. She also pairs very well with tanky engagers - cast your ult on them, and surprise enemies with hard engage! She shines in teamfights and skirmishes as long as there are tanks around.
Is Good Against: 
Champions that are bad at stand-up fights and mobility will naturally dislike Illyana. She can dodge everything they can throw at her, and Azir's ult, in particular, can be dashed through.
Is countered by: 
Obviously, Champions that are good at stand-up fights will naturally beat Illyana. The only steroids she has only increases her speed, not her damage.
Illyana, the Mirror's Edge Attack Power: 7/10 Defense Power: 5/10 Ability Power: 4/10 Difficulty: 9/10
Health: 554.12 (+89) Health Regeneration: 7.9 (+0.55) Mana: 304.1 (+39) Mana Regeneration: 6.2 (+0.45) Range: 125
Attack Damage: 56.72 (+3.8) Attack Speed: 0.682 (+3.2%) Armor: 21.4 (+3.4) Magic Resistance: 31.1 (+1.3) Movement Speed: 350
Primary Role: Fighter Secondary Role: Assassin
Recommended Item Builds
Assassin-like
Core: 
Situational: 
Melee Carry
Core: 
Situational:
Carry-Style Jungle
Core: 
Situational:
Engager Jungle
Core: 
Situational: 
Abilities
Note: The alternate names for Q and W (Illux and Basset, respectively) are from her lore. So if you wanna know why those names are there, read up. xD
Innate: Black & White Every third spell cast, Illyana creates an untargettable copy of herself that imitates all of her movement. It can cast spells, but they do no damage, and deals [80/70/60]% reduced autoattack damage. Lasts 3 seconds.
I suppose it's somewhat like a shaco ult/lb passive, but instead of controlling them separately, they move at the same time. The copy can't be targeted, so it's easier to know which one is the real one.
Q: Shadow Split (Illux) [60/60/60/60/60] Mana | [14/13/12/11/10] sec. Cooldown | Range: 275
Illyana dashes in target direction, summoning an illusionary copy that dashes in the opposite direction. The copy cannot attack but imitates Illyana's movement and movement spells. Lasts 5 seconds. Can be recast once to switch positions with the copy, including during/after Piercing Dark.
A mobility/mindgames spell that, by itself, deals no damage. This, in conjunction with her passive, means she can really trick her opponents with fancy footwork. This is pretty much Zed's W, minus the extra damage/range it gives Zed on his spells (Q, by itself, does nothing to augment her damage).
W: Piercing Dark (Basset) [40/40/40/40/40] Mana | [12/11/10/9/8] sec. Cooldown | Range: 450 | Line Length: 600
Illyana fires a shadow in target direction, dealing [80/140/200/260/320] (+1.0 Bonus AD) physical damage in a line. If Shadow Split's copy is active, both shadows are fired, with the second dealing 50% reduced damage. Shadow Split's recast ability can be used during this time to swap with the dashing copy.
Illyana's main damage tool/poke, it's a mixture of Zed's shadow+Q combo and Azir's W+Q. If you don't use Q, W is a generic line damage spell.
E: Quick Steps [30/30/30/30/30] Mana | [16/15/14/13/12] sec. Cooldown | Range: Self-cast/300 Teleport
Passive: Illyana passively gains [10/15/20/25/30] AD. Active: Illyana increases her movement speed by [10/15/20/5/30]% and attack speed by [30/35/40/45/50]% for 6 seconds. During this time, every second autoattack on the same Champion causes Illyana to teleport to her target, and casting a spell refreshes Quick Steps' duration by 1 second (can be increased up to 9 seconds).
Somewhat generic steroid. I added the teleport so that it's much harder to kite Illyana. The range is much shorter range than Flash (only 300 Range, which is 125 units shorter than both Flash and Ekko's teleport-auto). I tried not to overload her regular spells, 'cuz her ult is a doozie.
R: House of Glass [100/100/100] Mana | [90/75/60] sec. Cooldown | AoE Range: 1000/1200 Target Click Range
Illyana causes herself and nearby allies to transform into target allied Champion for 10 seconds. During this time, all the transformed allies use the average of all of their Movement Speeds + [10/15/20]%, Health + [150/200/250], Mana + [150/200/250], Armor + [15/20/25] and Magic Resistance + [15/20/25]. All other stats are averaged (except Crit Chance and CDR, which use the original Champions' stats). Attacking or casting spells breaks the illusion. Taking damage does not break the illusion.
I'm sorry, but Trickster's Glass needed to stay in some form or other. It was such a fun item to use (especially if your entire team had one!). The aforementioned house of mirrors dream + Trickster's Glass is what inspired the ultimate. The averaging of the stats is a weird thing, but honestly, it's mostly there just so enemies can't tell the difference between the characters (unless you look your opponents' crit chance or cdr. Is that even possible?)
The possibilities with this spell are endless. Since you literally can't tell the difference between a real and fake Champion, you can all turn into a squishy, use a tank to bait engages, or all transform into tanks for disengage. 10 Seconds is a pretty long time to stay transformed, so you can really play mindgames with Illyana.
So that's it, I guess. Honestly, the kit itself might be somewhat underwhelming, since it's the lore/backstory that I put the most effort into. Feedback is appreciated. Here's a jamming Cubone for your time.
http://38.media.tumblr.com/tumblr_lqp661V9ZO1r0mhfro1_500.gif
