Champion Concept: Marrow - The Shade of Oblivion (Please comment your thoughts)

I don't have an image of this champ yet again, I am making two champs with the pale, teenage, dark hair, male concept, the first one being of a dragon description. I was making two to see which one you all would be interested more, not only we have been slacking on the Demacia and Noxus war lately (despite the god king event), but we haven't been looking into the Shadow Isles in a long time. So time to make a champ that survived the curse (like over here). The design would be what I said above already, but with the black mist coming from his body, wearing something of a cloak, hood and a mask ( the hood with mask can be taken on and off in-game with ctrl-5 like kai'sa). Have fun with talking about a survivor from the Shadow Isles, while using its mist to his advantage.

Info: Role - mage lane - mid secondary lane - bottom damage - AP

Moveset:

Passive - Shadow Burst: If Marrow lands an attack on an enemy champ, they will be marked with "Shadow Blight" for 6 seconds, which reduces their attack and movement speed slightly, while depleting their mana over time by a minor amount. If marrow lands an ability on a champion already marked, it will have a bonus effect correlating to the ability, also increasing damage, but negates the status effect until it applies again.

Q - Black Blast: Marrow takes 1.5 seconds to cast a cone shaped attack in the form of the dark mist, dealing AP damage while slowing the target by 10%. When marked by Shadow Blight, the enemy champ hit creates a shorter range version of the same attack coming from them, dealing damage to the opponent causing the blast, but most of the damage fired out in the cone shaped attack (this can apply to more than one champion at once).

W - Shade Blaze: Marrow fires a beam made of the mist of the Shadow Isles in a straight line in a long, thin range, damaging all enemies caught in the beam with AP damage. When marked by Shadow Blight, the enemy champ, if they are near the beam, the beam will split off into a strand of shadow mist, dealing damage to the enemy champ, but on a smaller scale compared to the beam itself.

E - Dark Tendrils: Marrow fires out Strands of the dark mist from around him, firing them at a target enemy champion, rooting them.

 When the enemy champ is marked by shadow blight, Marrow can land the attack in a much longer range, also pulling them toward him up to an extent, but the root being a bit shorter. If the root breaks, it causes a blast of dark mist around them, damaging more enemies caught in the blast.

R - Wrath of Shadows: For 12 seconds, Marrow creates a dark field around him, all enemies in the field are slowed and permanently have the Shadow Blight as long as they are in the field, along with all of Marrows abilities' cooldowns cut down to half, excluding the ultimate of course. R passive: Shadow Blight now lasts for 8 seconds long, and can reveal invisible champions if they are inflicted by it.

Hope you like this champion idea, comment your thoughts below on this.