Samus Aran - The Galactic Bountyhunter (For THE RIVER KING's crossover contest)
https://upload.wikimedia.org/wikipedia/en/2/21/Metroidprime3_1.png
Lore:
Samus Aran's home planet was attacked by space pirates led by Ridley. The pirates killed everyone except Samus and in doing so created their worst enemy. After the loss of everyone and everything she knew, an alien race called the Chozo took her in and trained her as a warrior. To survive the harsh conditions of their home planet, the Chozo modified Samus's DNA by using their own as well as gave her the power suit which made her much more powerful than any normal human. After her training was completed at the age of 14, she joined the Federation Police to combat space pirates. She then moved on to the Federation Army after learning of a plot for pirates to attack the Chozo home world. Shortly after joining the army, she deserted after the death of one of her friends to become a solo bounty hunter. She is now known across the galaxy as the most capable bounty hunter there is who can accomplish any mission no matter how impossible it seems.
Here is a trailer from the Metroid Prime games if you never played them. https://www.youtube.com/watch?v=u8klx34R8m8#t=136.816245
Base stats
Health: 540 - 1951 HP/5: 6 - 19 Armor: 20 - 59.5 MR: 30 AD: 57 - 98 Attack speed: 0.59 - (+65%) Movement: 330
Secondary Bar - Energy - 25 points Samus gains 1 energy from nearby slain minions and from auto attacking champions and 5 energy from champion kills and assists.
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Passive - X-Ray vision
Bushes and terrain do not inhibit Samus's vision within her personal vision radius.
This does not reveal enemies to allies so only she can target enemies sitting in bushes with this passive.
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Q - Charge blast; Cost - 5 energy; Cooldown - 15 seconds; Damage - 100% AD (+5/6.5/8/9.5/11% per 1/4 second charged); Radius - 75 (+20% per 1/4 second charged); Range - 500 (+5% per 1/4 second charged)
Samus roots herself for up to 5 seconds while she charges an energy blast that grows in size, damage, and range the longer it is charged. Reactivating releases the blast which detonates upon hitting the first enemy and deals damage to all enemies within its radius.
For clarification, moving while channeling will stop the channel short. The cooldown starts after the shot is fired, not when charged. She can hold onto a charged shot indefinitely. Firing a charged shot resets her auto attacks.
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W - Grapple beam; Cost - 5 energy; Cooldown - 20/19/18/17/16 seconds; Damage - 50/80/110/140/170 (+50% AP); Range - 850
Samus shoots a grapple beam from her arm that pulls herself to terrain or roots an enemy for 1 second. If the targeted terrain is under a 20 degree radius from her position, she will fling past it for the same range that she pulled to it.
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E - Heat-Seaker/Super missile; Cost - 5 energy/1 missile; Cooldown - 5 seconds; Missile recharge - 15/13/11/9/7 seconds; Damage - 60/90/120/150/180(+60% AD); Range - 700 in 30 degree cone; Blast Radius - 100
Samus can hold up to 5 missiles at once.
Killing an enemy champion will cause them to drop a missile pack which full replenishes Samus's missiles when she steps on them. These packs can be destroyed if an enemy stands on them for 2 seconds.
Samus preps her arm to shoot a missile. After a 0.5 second delay, a heat seeking missile is fired in the target direction that seeks out the first enemy in range when it was fired.
If reactivated before the missile fires, Samus will consume 5 missiles at once to fire a straight line missile blast that explodes upon hitting terrain or enemy champions. The blast penetrates 30% of the target's armor.
Cost - 10 energy/5 missiles; Range - Global; Blast radius 200; Damage - 120/180/240/300/360 (+100% AD)
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R - Morph; Cost - 0; Cooldown 5 seconds upon returning to human form
Samus changes between ball and human form.
Can't use auto attacks in ball form but gains 30/60/90 armor and magic resist and 30% tenacity
She starts with R at level 1 like the other shape shifters.
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Q - Morph Ball Bomb; Cost - 5 energy; Cooldown - 1 second (unaffected by CDR); Damage - 70/105/140/175/210 (+60% AP, +50% AD); Radius - 150
Samus leaves behind an explosive that detonates after a 1.5 second delay. If Samus is on the bomb when it explodes, she is breifly sent airborn able to jump walls.
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W - Boost Ball; Cost - 5 energy; Cooldown - 5 seconds; Speed buff - 50/60/70/80/90%
Samus gains a short burst of decaying movement speed towards a target direction for 2 seconds that impairs her ability to turn. (like Sion's ult)
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E - Power Bomb; Cost - 5 energy/3 missiles; Cooldown - 10 seconds; Damage - 100/140/180/220/260 (+80% AP, +50% AD); Radius 300
Samus uses missile ammo to place a powerful bomb that detonates after a 1.5 second delay with increased damage and radius. Affected enemies are slowed by 30% for 1 second.
I think she would be most commonly played in middle lane due to long range artillery type abilities and moderate mobility with her W to allow her to roam.
Her build would likely look something like
or 
Other Concepts for the contest: Jack Spicer, the Evil Boy Genius by Vanic998 Axel, the Flurry of Dancing Blades by AFK Trash Sassy Natu by PhoneS Bowser, the King of Koopas by Echoing Wario, Treasure Hunter Extraordinaire by Doctor Fail Kamek, the Magikoopa by Chicken Dynasty