This is one of my first idea's for a champ, so don't expect something awesome or something.....
There is a place between dimensions and between worlds. To some it is known as the Outside, to others it is the Unknown. To most, however, it is called the Void . Despite its name, the Void is not an empty place, but rather the home of unspeakable creatures. Mekh Rajil is one of those creature. His mere presence even sends creatures of the void running. He had been poking at the walls that divide dimensions for a crack, a way into Runeterra, where he can command his army of unspeakable creatures to ravage and lay waste upon the world. He is called the Voidborn, similar to Cho'Gath, creatures so ancient and terrible that they have been removed from history altogether.
Within a decaying cyclopean city, a portal was opened as Kassadin absorb the power of the void. Sensing the evergrowing energy that it emited, He got through. Finally in Valoran, he spread chaos to every village he went through, turning any man,woman or chlid that tried to stop him into a souless army of semi-voidborns, but was eventually stopped by the Institute of War with the help of Malzahar. Now, joining the league the beckons to turn even the smallest creatures into his slaveless army and destroy the world as we know it.
"Beware of his claws, for even the slightest touch, or even glimpse, and you may never see the light of day again" - Malzahar, upon seeing him for the first time.
I know... the lore kinda sucks
Appearance: Kinda looks like Omen but with bigger front limbs and bigger claws
(Passive) Devour :
Upon killing an enemy champion, Mekh Rajil gains a stack of Devour (max 3), healing (lvl1 :5%/ lvl7 :7%/ lvl14 :10% per stack) of his max health over 7 seconds.
(Q) Nether Claws :
(Passive) His basic attacks deal bonus magic damage based on 5% of the targets current health.
(Active) Mekh Rajil empowers his claws for 7 seconds, infecting any enemy he attacks with Nether Venom, dealing X magic damage over time for 3 seconds. If the enemy dies within the effect, they will have X% chance to spawn a semi-Voidborn with X% of all of Mekh Rajil's stats. Last for 5 seconds.
(W) Void flame :
(Toggle) Mekh Rajil breathes out Void fire in a large cone, briefly silencing and dealing X magic damage to units caught in the fire and X magic damage for 3 seconds afterwards. While spell is active. Mekh Rajil reduce any cc effects on Mekh Rajil by X%.
(E) Oblivion scales:
(Active) Mekh Rajil creates a shield that absorbs incoming damage by X and slows the movement speed and attack speed of any nearby enemies. Shield last for 4 seconds.
(R) Void monstrosity:
(Active) Mekh Rajil hardens into a cocoon for .75 second, becoming untargetable for the duration and slows nearby enemies. After that time, he burst open, dealing X magic damage and turns into a demonic monster, gaining massive life steal and spell vamp and also gains AP and attack speed (semi voidborn doesn't recieve bonuses). Any current or spawning semi-voidborn on the duration turns into Voidborn, prolonging their duration to 10 seconds and gaining massive movement speed. Last for 9 seconds
So... tell me what you think :D